The closest post office to me unfortunately, with only one self service kiosk that's always off for some reason or out of service. This causes this Diamond Bar location to always have long lines, and there's always this one employee working their hardest (the woman working on 4/10/26) to get thru the line. Sometimes if you're lucky there would be two people. Parking is usually fine, sometimes the lot will get full so you'd have to wait or park elsewhere near the plaza. Check out the Chino Hills location, they have 3 self service kiosks and i've never had any issues with wait times/downed kiosks there. Plus the parking is never an issue there. read more

This place needs to seriously close down. Its a ghost town during their "operating hours". Packages are always lost or they put a "sorry we missed you" but they don't even attempt to make the delivery. Misuse of funds to keep this place open honestly. Have even noticed packages with tracking numbers marked as "delivered" but theres no sign of a postal worker at that time delivering mail. The other night I even saw a postal truck driving back to our street at 9pm, delivering another package. There is no accountability for them delivering the mail. read more

As a long-time resident of this community, I felt compelled to share what I witnessed during my recent visit to this post office. I wasn't the customer involved, but what I saw was disturbing and incredibly disappointing and I hope this reaches the right audience.  A customer came in seeking clarification about a notice they had received and wanted to resolve the issue. While I don't know the full details of the situation, it was clear that they were simply looking for answers. Unfortunately, the supervisor, who identified herself only as Kelly and refused to provide her last name, handled the interaction in an unprofessional manner. Her tone was rude, dismissive, and demeaning throughout the conversation. What stood out most was that she appeared to contradict her own explanations, and when the customer questioned the inconsistencies, she became defensive instead of trying to clarify the issue or resolve their concerns. A supervisor should be there to support both the staff and the public, and this interaction reflected neither professionalism nor respect. It's disappointing to see this level of customer service at a local post office that serves our community. Residents deserve to be treated with courtesy and professionalism, especially when they are simply seeking assistance. I sincerely hope management addresses these concerns so that customers can have a better experience in the future. She is a terrible example as someone in her leadership role, and the community. read more

Considering this location is already at 2 stars, I don't think my review will really matter much but I just need to say something because I was absolutely infuriated by the older women closing today on 7/20/2026 just before 6pm. My mother in law (an older women) walked in 2 mins before the posted closing time. All she wanted was to use the SELF SERVE vending machine to purchase stamps. This is less than a minute task, however once she was already in the location and walking towards, again the SELF SERVE machine, she was greeted by the incredibly rude women who literally shoved her out of the location while saying they were closed. My mother in law said she just needed stamps and the woman replied, "we have no stamps" and promptly shut and locked the door on her face. First off, she had two minutes and was already in the location. Secondly, where's the customer service or at the very least a small amount of compassion for an older woman trying to just use a self serve machine. She didn't need your help in anyway whatsoever. Like let the lady get the f'ing stamps and you could still close and leave on time. Now some might say why are you trying to go and get a service somewhere right before they close. This is not the case. My mother in law actually had another package for delivery but she insisted we wait because she didn't want to inconvenience the workers so close to end of the day. See how compassion works? Thinking of others? Being, I don't know, helpful. Serving the public. So in case the post office is looking for someone the teach their workers how be polite and considerate, you can ride along with me and my mother in law while we run errands and you can observe how she kindly treats others. I'd bring a big note pad though cause you need a lot of help. K byyyeeeee. read more

I have to admit that the management or system used for 2025 during the busy season (November-December) have improved substantially compared to the last 10 years. The key thing was keeping the drop off bin free of packages getting stuck especially for those that drop off ton of packages. Otherwise you'll have to wait in line just to drop off which could be worse when there are only 1 employee working the front. The most annoying thing would be that the outer door can be locked at times before 9am which means you can't access the drop off bin or PO Boxes earlier. read more

Very disappointed with my local USPS delivery service regarding an important certified passport-related letter that required a signature. I paid extra for expedited handling and expected a proper delivery attempt. Instead, the carrier left a PS Form 3849 notice in my mailbox marked "dogs" and left immediately without ever ringing the doorbell or attempting contact. I reviewed footage from multiple security cameras around my property, and the video clearly shows there was no actual delivery attempt made. This was a certified letter requiring a signature, not ordinary mail. Customers pay additional fees for reliable and professional handling of important government documents. Simply writing "dogs" on the slip without even attempting to notify the resident is unacceptable. What makes this even more frustrating is that this has happened multiple times already. Now I have to waste additional time driving to the post office, waiting in long lines, spending more money on gas, and rearranging my schedule just to pick up something that should have been properly attempted at delivery in the first place. The entire incident was recorded on camera, including the carrier walking up, placing the slip in the mailbox, and leaving without knocking or ringing the bell. USPS seriously needs to ensure carriers are following proper delivery procedures instead of skipping delivery attempts altogether. read more

US Post Office - Certified passport letter marked "dogs" with no delivery attempt or doorbell ring. Entire incident recorded on camera. - Post Offices Near Me - Diamond Bar, California

Warning I don't know why but they paddle locked the postal boxes you can't even drive through and use the drop off It's locked so forewarning before you go there you'll know you have to park which is difficult. read more

I don't know what worse... this post office or the dmv...people are always waiting and only one person working the spot.... read more

US Post Office - This post office is notorious for not manning their post... and just leaving everyone to wait while they move on their own time... - Post Offices Near Me - Diamond Bar, California

This location is always so busy, I typically come in once a week to drop off packages and parking can be tricky. Drivers are not conscious of the lanes or the entrances and exits. When I go inside I like to use the drop off box, but it gets fully pretty fast or it gets jammed, when that happens I try to get the attention of a postal worker and leave it at the counter, for such a busy place they often only have one person working the counter. read more

I am extremely unhappy with their service. Not just once, but several times, they lost my packages. I had to spend a lot of time chasing after them, only to find out it was because they misplaced them, didn't even know where they put them, and yet still had the audacity to assume it was my fault. Some of the packages were urgent, making me almost have a heart attack. However, they showed no remorse whatsoever, instead telling me that at least I received my package. Little did they know that I had bought fresh groceries and left them in my car on a hot day, and because of their incompetence, almost all of my groceries were lost. Spending a lot of money every month only to receive this kind of service is incredibly disappointing. read more

First time visiting this location. I usually go the usps in Walnut on Lemon but I was near the Diamond Bar location running errands. I walked in and there were two people ahead of me in line and a customer being helped at the window. No other employees were present. The employee who was helping the customer at the window excused herself and didn't appear for at least 10 minutes. Also heard laughing from employees emanating from the back. Instead of working, it sounded like the employees were partying. Meantime, more people filing in. I removed myself from line and left. This place is ridiculous. I went to my usual usps in Walnut and as usual, didn't have any issues whatsoever. read more

I wish I could only say good things about this post office, but I noticed recently that the post box area/with access to package drop offs is no longer accessible on Sundays, and possibly closed entirely after hours on all other days. I respect the service that these folks do and perhaps the limited hours and possibly a staffing might have been reduced affecting the quality of service. The PO people are always nice, but it's unfortunate that services have been limited. Mail service is always appreciated but I truly hope this can get better. read more

Customer service is not good at all in the post office. Communication because of mailboxes being broken into at my home is not possible with person in charge here at this location. read more

This place is always busy , that why I do drop off. The workers was helpful. The place has spacious parking with handicap spaces . Not service requested since I as dropping off only . read more

This is my go to post office! Keisha is always so welcoming and sweet! They work so hard and always have smiles on their faces! Sometimes they are alone so it's important to be patient and give them grace! read more

There was only one person working, sorta a long line. But the female working was quick with it and nice. Choose here !!

Awful service. Long lines. This place has never improved. Grumpy government workers. Service is just miserable. Some customers cut in line by just walking up to counter while workers don't say a darn word. Avoid this place! read more

I went in the morning twice to buy stamps, but both times they claim they were out of stamps and the second time they said the safe hadn't been unlocked to retrieve the stamps. read more

I have been in and out of this post office for many different issues but one revolving issue is always never have enough stamps. So a few months back I decided to get a larger amount of stamps so I don't have to always come back here. They have an automated machine that had no one waiting at and I decided to try it out. You can buy forever stamps here which I did and it was simple and fast! But it was surprisingly empty which to me was amazing. Parking spots are plenty! read more

For some reason (within the last 6 months or so), this Post Office decided to remove the two drive-up and drop off mail boxes, so now you have to park and get out of your car in order to drop your mail into the mailbox. The mailbox just outside the front door only accepts letters, so if you something larger than a letter to mail, then you'll have to go inside to mail it. Not very convenient USPS! Xie Xie! read more

THE STAFF KEEP STEALING ALL MY PACKAGES, DONT COME HERE!!! I had all my wedding stationery and custom made gifts for my bridal party delivered on 3 separate days this past week, tracking says it was delivered inside my apartment mailbox locker that only myself and our mailman have a key to. On 1/31, 2/1, and 2/3 they were all said to delivered inside my locked mailbox but when I checked each time my mailbox was empty. After a whole WEEK, not a single thing in my mailbox not even an advertisement (which I receive a lot of almost every day).. when I tried asking the staff about it they shrugged and said it probably got stolen. there's NO WAY my package could've been stolen from my LOCKED apartment mailbox literally right after I get a delivery notification when the only other person who has a key to my mailbox is the usps staff and they are the ones who just marked it as delivered. Not only that but when I do receive packages they are already torn open. When I came to complain I saw another man complaining how his package that got delivered to his house was ripped open and empty. They just scanned the empty packaging as delivered and left it at their doorstep. The fact that the staff didn't seem surprised or even cared and said "this happens all the time" is very suspicious. after reading all the other reviews here , I can see this post office has a serious theft problem. Very disappointing that they really stole all my wedding stuff that they can't even use LOL read more

US Post Office - all my packages were stolen on 3 different days from my locked mailbox that only me and the mailman have a key to - Post Offices Near Me - Diamond Bar, California

what a shame..... i shipped out my package at the diamond bar location, and it never moved ahead... it still shows in the location, it been over a month. Seemingly someone in the staff took it with them, or got misplaced in the location....who knows. The Manager has no courtesy to call back and the supervisor has nothing to say Why have these posts if there is no one to talk to or take responsibility. As a customer one has to run pillar to post with no help ABSOLUTELY DISGUSTING WITH NO PROFESSIONALISM GO TO BREA USPS AND CHECK OUT THE STAFF AND HOW PROFESSIONAL THEY ARE this usps office seems as if we are in some village read more

AVOID THIS USPS AT ALL COST!! I've dropped off several packages at this post office in the past few weeks and they're unreliable. They tell you to drop off your package to the side counter and this is pretty normal at most post offices I've been to except they don't scan your package. 3 of my packages that have been dropped off at this location display that they've never even been in Diamond Bar, hell I've had a package go missing for 2 weeks, it's about to be 3 next week and there's no receipt that it was even at this post office because they DONT scan. The supervisor was very nice and trying to help with my missing package except all she could tell me was that they never received this package and can't track it. I definitely dropped my package off at this location where they specified where to leave all packages and obviously it can't be tracked because they never scanned it.. Honestly just avoid this place if you're sending out something important or just wait in line and make sure you get your receipt that the package was dropped off. I'll be avoiding this place indefinitely and make the drive to Walnut USPS. read more

Stopped by to mail out my sister's bday gift. The older heavyset female rep "helping" me was a complete B without any customer service skills, was rude beyond all measures and was absent of any solutions whatsoever. She questioned why i didn't leave the paper attachment with the certified stamp; investigated as to what EXACTLY was in the package; continuously asked the same questions repeatedly if i wanted tracking or signature, as if she had no memory cells.... 2/5 for this Post Office because of her. She's a piss poor example of a Federal employee. read more

Great friendly local post office. This place is always welcoming for any postal need. The staff here is exceptional, they are patient with all needs and truly are here to serve us all. With the current pandemic the staff has worked tirelessly to keep everything safe and on time. So far everything that I have sent out despite the troubles with logistics have arrived on time and safety. They did a great job with extending my mail hold when I could not make it back home and the USPS website did not reflect the correct hold dates due to bugs. Please come and support this location. read more

UPDATE: I came here to drop off a package that I wanted to mail out by weight since it was so small. I didn't have an envelope on hand, so I flipped the flat rate envelope inside out, wrapped it up nicely. Walks up to the tall black lady that looks like she's from OITNB, she said no you can't use this envelope because we're going to think it's flat rate spoken with attitude. Okay, it's completely covered, none of the flat rate portion is showing and she still told me to use an envelope. I've done this before at other locations, this one just seems so anal about it. Not a recommended post office if you are trying to mail out something requiring their help. Previous Review: I came here today to drop off a package. I already had the pre-paid shipping label. All I wanted was a receipt, I walk up to the black lady and ask her to scan my package. She told me to wait in line, 5 mins later a MAN WITH 30 boxes comes in to drop off, walks up to her and she SCANNED HIM and left. I waited for 40 mins just to get a receipt, while a guy who comes in here just gets it done within one min. The manager didn't do anything, she just stood there and watch the line get longer and longer. Management here is shit. read more

US Post Office - Everytime I wait in line and stare at the workers there. - Post Offices Near Me - Diamond Bar, California

The service was alright not fast and not slow. Nothing to address . The staffs seem nice but seems like the don't want to there.

Every time I've went I've been greeted with slow, long lines and condescending staff. There are only two staff working the desks which does not help the long line, and like others have said they're usually not very helpful and are rude. The last time I went only one of the two people working was friendly, the other one was not nice at all. Go to cyclone postal instead, super fast and the guy working is always nice and helpful. read more

The service is OK, but for some reason overseas postage always cost a few dollars more than say for post office in Brea or Rowland Heights for the same goods sent overseas. read more

Overall, the postal workers here are nice and helpful. I mail out packages, pick up mail, buy stamps, etc. Sometimes there are communication issues with other postal offices and carriers that the workers here are having to coordinate with, but it's ok, things happen. The workers here really do their best to provide good customer service. read more

The worst. Never had an old experience at this location. Can't even help tape up one tiny bag. The lady was not friendly at all.

I understand there are a handful of people with negative experiences with the usps, but so far they have proven time to be quite reliable when it comes to mailing items and receiving my online purchases from ebay, and other sellers from the marketplace. Not too long ago I had a package that was bouncing back and forth between distribution centers and after calling Customer service with a claim #, I was contact by the local USPS to further investigate and claim the item being bounced around. In short I did get my package, and it turned out to be the shipper's error when he first placed the package slip on the side of the box where the bar code got scratched. All my other packages came through safely and there were no damages to them especially with delicate items I work with. Did i mention that their gift shop (online) has some awesome merch? Honestly affordable and would make great gifts. read more

The Diamond Bar post office is the ONLY post office in the area I will go to. They are always friendly and efficient. Never had an issue there. All smiles from the postal workers. I usually go in their with pre-paid packages for scan and receipts. In and out usually in a few minutes, even when there is a line. On the flip side...I live in Phillips Ranch/Pomona and the post office at 580 W Monterey Ave, Pomona is horrible. They have the worst attitude and won't even answer their phone! I actually have to call the Diamond Bar post office and have them call the Pomona post office to get them to pick up their phone. Not joking! Have a problem with your carrier misdelivering your mail or packages to the wrong address? They could care less. Pomona just doesn't care. On a Yelp scale of 1-5, I would give the Pomona post office zero stars. read more

Received an email from USPS of their fail attempt to deliver a package at my location at 5:22 pm on Sat 30th May which we were home and I have a Ring Camera Door Bell that would notify me if someone is at my front door; in addition, would record the event that I have no recording of the fail delivery attempt. I called the Diamond Bar Post Office in the hope I could pick it up instead so the package doesn't get sent back but made 4 attempted to call and it kept ringing for 5 mins and hang up. Also called the 800 number which was useless as it gave me the runaround with no resolution nor the ability to talk to an agent. I know they are understaffed but at least allow us to leave a VM in the hope someone would call back at their earliest convenience but that is not the case. I have to drive to the post office hoping it is no "en-route" for pick up. read more

US Post Office - Post Offices Near Me - Diamond Bar, California

Been coming here to drop off letters and packages forever... Grew up in the area and still work in the area. Love the familiar feeling of seeing the same people at the counter and also having them recognize me. They are usually way faster than the Walnut USPS. Usually whenever I come during lunch, there are more than 2 people at the counter. It's been awhile but I'm still not a fan of the slant parking because that means that there is only one way in and out if you need to park and head inside. The opposite traffic is the only way for one to drop off mail at the mail box and exit the USPS parking lot to Albertsons or to Diamond Bar Blvd. read more

This has got to be the worst post office ever! I am talking about home delivery! We always have a different mail carrier and always get our mail at different times! When we lived by Walnut Elementary we always received our mail at the same time and had the same mail carrier! I was expecting a very important letter on Thursday or Friday! We didn't receive it so I thought I'll get it Saturday!!! WELL IT MUST HAVE BEEN A HOLIDAY BECAUSE NO ONE ON OUR STREET RECEIVED ANY MAIL WHATSOEVER ON SATURDAY!!! I will start using UPS or FedEx instead for my important things!!! I only gave 1 Star because I had to so that I could post this!!!! read more

I had a package where the post master left a note at my postal box because I wasn't at home. I went to Rowland Heights AND Diamond Bar Post Offices, and neither had the package. I was told to wait because the carrier might have the package. It has been 3 days and nothing showed up. Calling to the office always gets unanswered. Calling to the 877 numbers was useless too because after waiting on the line for 40 minutes the lady told me she knew nothing about the package and I had to call the local post office. Yes, I agree that USPS should be totally bulldozed off and rebuilt, but unfortunately it will never happen. read more

Already did a Google review. I don't tend to give bad reviews but really?!? Terrible service here. The staff don't like to interact with people. I tried being pleasant and respectful every time but even with a smile I can't seem to get them to talk a respectful way. Managers please train your employees and hold them accountable to behaviors that are observable and measurable. They are getting paid to provide a service to customers. If they don't want to work at the post office there are plenty of people who are looking for jobs and would grateful to just get paid. read more

The person I spoke to on the phone tried to help me, so she gets 4 stars. The USPS gets 1 star. I just called the phone number listed on yelp, which is (909) 860-2469, and I spoke to a real person in this office. She was trying her best to help me with a parcel that a carrier failed to deliver while I was waiting at home all day to sign for it and he never showed up (uggghhh). She wanted to call the carrier, as he was still out on the street, but being that this happens to be this office's first day handling mail for my city, Rowland Heights, they have not organized themselves enough to even have the phone numbers of all the carriers that now work from the Diamond Bar office, so she couldn't even try to call him. The USPS continues to be disorganized but this lady, who was kind enough to listen to my problem and try to help, she's good people. I think her name is Fern. I used to be a carrier and I know how frustrating the job can be. Now, I wait until Monday to get my much needed medication from the post office myself (instead of waiting at home all day long again). I definitely left negative feedback as USPS.com, too, for this carrier who didn't even try to deliver my parcel, didn't even leave a notice, but scanned my parcel as "delivery attempted" anyway. Liar. read more

I truly believe that if they worked out some of their kinks, it could be so much more efficient. I've come to this post office for years now, recently started mailing stuff out when I opened an online store. For the most part it's the most reliable since mail gets collected much more often than the other mail boxes around the city. Getting packages is also relatively okay too. The lack of good experience mostly stems from the inefficiency of actually being there. 12-14 years ago I remember the drive-up mail box for regular mail used to be on both sides on going and incoming from the plaza entrance. But then they ended up taking it out because of theft and prompted to install a regular mailbox at the front door, they said they were "working on it" on making a different method for the drive-up one. It felt like it took them almost a decade because the new mailbox wasn't installed until some time this year. LOL. They also took out the regular mailbox by the front door "because it's no longer needed". I really thought they should've left it because they lock the new drive up mailbox after 5PM and on weekends to prevent theft... Even though the box itself was redesigned so that it was harder for mail thieves (??) So I can't even mail my stuff during weekdays because the mail box is locked (I can only make it after I get off work), now I always have to leave earlier in the morning to make a pit stop at the post office if I want to mail my orders out or wait until Saturday mornings. It's also only on one side now so I always have to make a u-turn to drop off at the drive-up one. I wish they would've kept the dual direction drive-up mailbox method, would help being more efficient driving direction wise. Then the few times I do make it a few minutes before 5:00PM, they still won't let me throw my mail in the drive-up mailbox (even though they were collecting the mail) because they "can't take mail directly from people", even though I asked if I can just throw it in her box that she's collecting mail into. She denied me and told me to put it in the collection box at the front door. I was confused because that mailbox was taken out. The only one left was the priority express mailbox, which people usually pay extra for. I stood there looking for another box thinking maybe there was another one she was collecting mail with. Then she came up and told me in this tone like I was stupid that "its the one right in front of me", she meant the priority express one. I was extra confused, asking if she was sure. She sounded exasperated and told me 'yes'. It seems like they mix both regular mail and priority express mails together... Even though it would be faster if they collected the two mail boxes separately so they don't have to sort it out later. (??) Then the line at this post office is 90% ALWAYS long and it takes forever. I think maybe it's because it's a central hub one (and not one of those smaller post offices) so there's always people shipping stuff or having issues with something. Luckily I never have to stay long, I just find the way things are done sometimes is just... Very inefficient and slows a lot of the processes down. *Shrugs* read more