Valid Email Addresses
 

Interesting -- well, I found it interesting -- article on what constitutes a valid email address. I did not know:

I wonder if there are any email providers who would allow USER@domain.tld and user@domain.tld to point to different inboxes.

For the full article:
https://www.netmeister.org/blog/email.html

There are many web pages asking for an email address that reject legitimate entries. And I'm not talking about "<>"@example.com or ".jdoe"@[IPv6:2011:470:30:84:a276:63ff:ef72:3888]. I mean quite often plus addressing is disallowed :eek:

I suspect very few honor the upper/lowercase difference. Would cause too much confusion. I receive forms every day from people and many type in the their addresses incorrectly to the point I have to look them up sometimes, but one of the funny things is how often people omit capital letters or type in all caps.

I always learnt that upper case or lower case characters make no difference in email addresses. Unless there's a recent technological change of some sort, it makes no difference if you writer USER@domain.tld or user@domain.tld

Upper case or lower case can make a difference in URL's.