> so, if I want to use mail.example.com as my fqdn, and the old fqdn was something.else and firstname.lastname@example.org was redirecting mail to email@example.com ... then what do I need to change in Exim to make this happen?
Is it maybe the aliases setting?
Probably you edited the \etc\aliases file, it defines where to forward mail to. There will be a line like:
After saving the file it needs to be processed by the command
If you skip this file then mail to root will go to the old forward address and will fail if that no longer exists.