I worked in company where the naming scheme was jodoe, j2doe, j3doe, ... We had a coleegue that worked in that company, moved to another, then the companies merged, and he was j2doe because he for some reson was forbidden to use his previous login. We also had logins like j8smith for the more popular surnames. Nobody cared.

Perhaps it'd be better to have john.doe1 and john.doe2, since someone who wasn't aware yet of the numbering convention may be confused by who used john.doe1. Or, they make a typo by leaving out the number and it goes to the wrong recipient.

But that would mean that everyone must get a number, even prokopis.papadopoulos1@.

People have names. I find that digit in the mail address that clearly consists of a name deeply degrading.

There are other ways to solve collisions: j.doe@, j_doe@, maybew one of those has a second given name, whatever.