I used to do this, but it is troublesome some times because some websites use libraries that strip or replace the plus sign and the final email ends up being an address that you don’t have access to.
Most of the time this is not a problem because you can create the account again with the correct email, but I have lost a few good usernames in some popular websites because I pulled this trick on them, Gravatar is one of these websites and the simplest one to explain.
I wanted a specific username that was available; I signed up with an email that looks like username+gravatar@gmail.com and the operation went through, then when I tried to log in, the website kept saying that the email was incorrect. I tried to reset the account using the username instead, which would force them to send a reset link to the email associated to this account, but the emails never arrive. I gave up that and other good usernames in many websites because of the inappropriate handling of email addresses by some popular web libraries.
Also, the same way you learnt this “trick” other programmers discovered it too and implemented a stripping algorithm to remove the unique ID during the registration process, so it is not very useful nowadays unless the website is very obscure and their developers either are rookies or do not have time to prevent this.
Reputable websites don't have an incentive to strip out the ID. It is only websites like "sold out" dating websites or otherwise nefarious websites that have that incentive in the first place. So, name+id@domain.com is still useful for filtering and indexing, and in fact if a website does strip out the ID you should ask yourself why would they need to do that.
I was once at the receiving end of business talk clearly addressed to someone else on my gmail account.
At first I believed it was some scam but it soon got clear that my account was accidentally siphoning mail from someone using this supposedly clever scheme...
Most of the time this is not a problem because you can create the account again with the correct email, but I have lost a few good usernames in some popular websites because I pulled this trick on them, Gravatar is one of these websites and the simplest one to explain.
I wanted a specific username that was available; I signed up with an email that looks like username+gravatar@gmail.com and the operation went through, then when I tried to log in, the website kept saying that the email was incorrect. I tried to reset the account using the username instead, which would force them to send a reset link to the email associated to this account, but the emails never arrive. I gave up that and other good usernames in many websites because of the inappropriate handling of email addresses by some popular web libraries.
Also, the same way you learnt this “trick” other programmers discovered it too and implemented a stripping algorithm to remove the unique ID during the registration process, so it is not very useful nowadays unless the website is very obscure and their developers either are rookies or do not have time to prevent this.