Postcrossing Blog

Stories about the Postcrossing community and the postal world

Viewing posts tagged "behind-the-scenes" View all


Good news, everyone! After many requests, we finally opened a proper PO box for Postcrossing. So, if you’d like to send us a meeting card, show us some cool mail-related item that you found, or just say hi using a postcard, feel free to do so!

Here is the address:

P.O. Box 216
EC Tavira
8800–999 Tavira

We look forward to hearing from you! :)

P.S. – Depending on the volume of mail we receive, we might not be able to acknowledge all of it. So if you require an answer from us, the Contact form is a better way to receive a reply.


On the last behind-the scenes post, many of you asked how do we find missing Postcard IDs. Well… I’m afraid the answer is pretty straightforward: for every help request you submit, we compare the information you provide us about the postcard you’ve just received with all the information we have about the postcards currently traveling to you until we find a match.

There aren’t any magic tricks for this one – it’s just a matter of patience and sharp Sherlock-skills!

Let’s see how it works in practice. Imagine it’s 2005 and someone named “Ana” has just received a cute postcard from Portugal with some lighthouses… but sadly, the Postcard ID is wrong, and she cannot register it. She knows what to do though, and promptly submits a request for help with her unknown Postcard ID!

On Postcrossing’s back office, a page is created for her help request. It looks a bit like this:

Finding missing Postcard IDs

This page is only seen by us, the members of the Postcrossing team, and contains all the information we might need to find the right postcard ID.

On the top of the page, you see all the information Ana just submitted about the postcard: it features 3 lighthouses, was sent around July 6th, from someone named “Paolo” from Braga, Portugal, who mentions he’s an IT student.

Then, below that, a neat little table is displayed with all the postcards traveling to Ana. For instance, you can see she has quite a few postcards traveling to her at the moment: a few from Portugal (shown first, since they are most likely to match), one from Germany and one from the Netherlands.

Can you guess the right postcard ID for the card Ana received? Given all this data… it’s not that complicated, right? You just need to compare the information available to spot the correct postcard ID!

So it looks like PT-1 is the postcard ID she was looking for: the ID is very close to the right one, the name and location match, the picture the sender uploaded seems to fit… now all is left is to let the recipient know this information, which we do by clicking a button.

If enough information is provided, Postcrossing can sometimes automatically find the right postcard ID, but most of the time, things aren’t so simple — that’s where Vicki steps in. She goes over nearly 1000 requests every week, going after the really tricky cases and doing some remarkable detective work to make sure all postcards are registered. It’s a very time-consuming process, but a very important one as well, which minimizes frustration all-around.

So… what are the most common problems she has to deal with?

Most of the time, simple stuff: digits are out of order, a 7 looks like a 1, a number might be missing, someone wrote the ID of the next card they requested or there might be some confusion regarding country codes (CN≈CH, AU≈AT). Sometimes, in the excitement of sending off a postcard, someone will just forget to write down the postcard ID. Given enough information, the answer is usually straightforward.

But there are trickier cases — like when you receive a card from a private swap which you completely forgot about! Or when members don’t realize that the postcard they received was actually sent to a roommate or family member living in the same address… in which case, every family member should submit a request.

A few postcards do arrive after traveling for over 1 year… in which case they cannot be registered.

What helps? Here are some tips on how you can help make a search for a Postcard ID more efficient:

  • Describe the image on the front of the postcard you’ve received in as much detail as possible! If your description matches an image the sender has pre-uploaded, the search for the right Postcard ID will definitely be easier.
  • Can’t make out the exact name of the sender? Have a guess from the signature. Even if you write it incorrectly, we’ll probably be able to figure it out.
  • Look closely to the stamp and cancellation mark. Where and when was this card posted?
  • Does the postcard describe the sender, eg. what they do for a living, where they live, whether this is the first postcard they send? If so, include these on your help request!
  • Submit just one request per postcard received. If you want to add more information to it, just delete the request (you can do this on your Received postcards page) and re-submit it with all the information.

To prevent this situation, here are some tips of things you should do, which will definitely help your cards get registered in case something goes wrong:

  • Try to write the Postcard ID with a pen with water-resistant ink, so that it cannot be washed away if the card gets wet.
  • Write the Postcard ID on the left side of the card, and at least in two different places.
  • If this is a card for a private swap, or a thank you card – mention this on the postcard, so that the recipient does not confuse it with a Postcrossing card!

Every time a help request is submitted, the status of the search will show on your Received Postcards page. If it says “Searching”, then it is still in the queue and will be answered as soon as possible. If you manage to find out the right postcard ID before we gave it to you – congratulations, you must be a smart cookie! :) Just don’t forget to delete your request for help on the Received Postcards page.

Finally, it seems many people are still unaware that they can ask for help searching a Postcard ID… so if you see any pleas for help on members’ profiles, just pass on the knowledge and share the link to our special form, deal?


As promised, the first post on our behind-the-scenes series is about address validation. This is the process through which we check that all addresses in Postcrossing are (to the best of our knowledge) correct and complete.

The Little Mail Carriers helping us moderate addresses

“Red alert! Red alert! I think that one over there is missing the postal code!”

Addresses are one of the most important things in Postcrossing. Wrong or incomplete addresses would result in postcards being delayed or not delivered, and general unhappiness – which we would like to avoid.

There is specialized software to process addresses of course, but it’s either dodgy, specific to a country or just crazy expensive for our size. So, we chose to do this task ourselves, splitting the job between Paulo, Vicki and I. Each one of us picked a set of countries according to our strengths and learnt the UPU address format of those countries by heart. Most countries have their own format – and some are much simpler than others. We use this knowledge to go over thousands of addresses per week, spotting invalid ones, or just rearranging the order of the elements on the address. Most of the time, addresses will be read by automated sorting machines, which expect them to be written in a certain way. So if every address is formatted as UPU recommends, everything will go faster!

What makes an address invalid? Lots of things:

  • Parts might be missing: name, postal code, country name, etc.
  • The address might be written exclusively in the local script (Chinese, Thai, Cyrillic), making it hard to write for people who don’t understand that alphabet or those without a printer.
  • The address might be completely translated into English – which is usually a bad idea. For non-Latin scripts, transliteration works better and faster in our experience.
  • The address might not match the account’s location/country.
Technology helps with the last item on that list, because we can usually match your IP address to the location you’re signing up from. For instance, if a member with an IP address in Canada is opening an account in Fiji … something might be wrong, and we have to look into that. :)

A few postal operators also provide a list of all valid postal codes for their country, giving us the ability to automatically detect typos or invalid postal codes.

The Little Mail Carriers helping us moderate addresses

“Let’s just add the country name here at the bottom… I think it’ll help!”

The whole process of validating addresses has been streamlined over the years, but it still takes quite a bit of time, since every single new address needs to be checked and validated. We’ve been doing it for so long that by now we can tell at a glance whether an address is valid, incomplete or just in a strange order. We might not find all the problems – but we do spot lots of them!

Plus, we’ve learnt many nice things in the process too! For instance, did you know that an address in China should be written from the biggest component (province) to the smallest one (adressee) if written in Chinese characters, but the other way around if written in Latin characters? Or that there are no street names in Japan? Or that every house and building has its unique postal code in Singapore? It’s amazing!

I think that’s it for addresses, so I’ll leave you with one last tip: make sure that you write the address on your postcard exactly as it is shown – it’s already optimized for that country!

I hope you liked this first post on our behind-the-scenes series – we’ll get cracking on the next one! :)

Ana + Paulo @

“So… what do you do for a living?”

We get this question a lot, Paulo and I, especially at Postcrossing meetups. When we explain that we both run Postcrossing full-time, people often seem surprised to find out that the website doesn’t work automatically by itself. :)

Of course, static pages can almost run on auto-pilot, but Postcrossing is not static and it is constantly growing. Every minute that goes by, the website is being used and changed simultaneously by thousands of you, with hundreds of new members joining every day! At this scale, even some of the simplest tasks can be greatly amplified. Take for example, answering emails, finding postcard IDs, validating all the addresses or moderating the forum – these are some tasks which gradually became time-consuming for our small team.

But there are other, less visible things that we do, that are no less important. For instance: servers are maintained to keep the website running snappy and safe, code is developed, updated or fixed and we regularly improve our address selection algorithm so everyone can have a better experience. On the less technical side of our days, we keep in touch with postal operators, answer media queries and create content for this blog, among other things. So, overall, there are many small (and some not so small) tasks that keep us busy running the site.

Since so many people are surprised when we mention our job descriptions, we thought it might be interesting to show you what it’s like to run Postcrossing – and what it looks like “behind the scenes”. The first post on the series will be about address validation, and it will be posted in a few days.

Meanwhile, we’re collecting ideas for future posts, so this is your chance to chime in! Is there any part of what we do at Postcrossing that you’d like to know more about?