There are quite a few valid email addresses according to the standard that this flags as invalid.
A big one that I use quite a fair bit is the 'tag' feature
email+tag@example.com
Gmail for instance will send the email to the correct email address, in this case 'email@example.com' and label it with the 'tag' label.
So for instance, if you are subscribed to a newsletter, you could do 'fred+newsletter@gmail.com' and it will be auto-labelled with the label 'newsletter'.
It also fails with mailhost style routing, eg mailhost!test@example.com
There are quite a few valid email addresses according to the standard that this flags as invalid.
A big one that I use quite a fair bit is the 'tag' feature
email+tag@example.com
Gmail for instance will send the email to the correct email address, in this case 'email@example.com' and label it with the 'tag' label.
So for instance, if you are subscribed to a newsletter, you could do 'fred+newsletter@gmail.com' and it will be auto-labelled with the label 'newsletter'.
It also fails with mailhost style routing, eg
mailhost!test@example.com