My auto-reply email message worked longer than I did.
From 1997-2001, I worked for Verio. On my last day of work, I set up an auto-reply email saying that I’d left the company and providing my new contact information. A couple of years later, I mistakenly sent email to my old Verio email address. And I got the auto-reply message! In Verio’s defense, I should point out that I had two email addresses, one that I used internally, one externally (for press releases, articles, and the like). So my email setup was nonstandard, and the second address obviously escaped detection.
I then started checking the email address on each subsequent anniversary of my leaving to see if it was still working. The auto-reply email worked on the 4th anniversary of my last day at Verio but not the 5th anniversary. So it lasted somewhere between four and five years.
Which is how my auto-reply email message worked at Verio longer than I did.