I'm locked out of my 6 year old Chipotle account because they now say my email address is invalid when I login. Here is me asking for their help:
I also reached out to them on Twitter but they directed me to this form. I followed up with them on Twitter with what happened in this screenshot but they are now ignoring me.
Even that would be technically incorrect. I believe you could put an A record on a TLD if you wanted. In theory, my email could be me@example.
Another hole to poke in the single dot regex: I could put in fake@com. with a dot trailing after the TLD, which would satisfy "dot after @" but is not an address to my knowledge.
Something something http://[2607:f8b0:4004:c09::8a] and http://3627734062 are valid url's without a dot, and are probably valid for emails too, but I'm too lazy to actually verify that.
I believe you need a domain name (with MX records) for a valid email address, not just an IP address.
The right way to validate the domain, if you must, would be to perform a DNS lookup to check whether the MX records exist. Pretty much anything can be a valid domain name these days; it's best not to assume.
I've had issues with this in using govt emails too. DOD accounts all have multiple dots based on branch and dept. It broke so many systems and emails never went through.