As an undergrad at Cornell, I spent several years working for computer services writing an email system in assembly language for the IBM 370. The system was scrapped shortly after I left for grad school at Berkeley. After a year at Berkeley, I followed by advisor, Michael Sipser, to MIT.
I had email addresses at Cornell and Berkeley but I have long since forgotten them. At MIT I wanted the userid "lance", but the name was taken by Lance Glasser, then an MIT professor. So my email became .
When I graduated and went to Chicago, I decided to stick with the userid "fortnow" for an email of . This bucked the trend at the time of having first names for email at Chicago so I had to have aliased to . When the university started system wide email I got though also works.
When I did a sabbatical in Amsterdam my email became or simply . When I moved to the NEC Research Institute my email because aliased to and when the NEC Research Institute became NEC Laboratories America I got my current email .
In addition to this, the ACM has created permanent email addresses, permanent as long as you are an ACM member and I did create an address though I never did give it out (until now). My brother and I now own the domain fortnow.com and I have what I do call my permanent address, . I also am the default receiver for fortnow.com mail, which means that addresses like , or even will all go to me.
All of the email addresses in this post still work and forward to me. But I will stick to using two main email addresses, for work related email and for non-work emails.