The usual cause of this is that you have an alias that is being looped back to itself. Let’s explain.
Examples :
- `/etc/mail/virtusertable:`
sales@johndoe.com -> Sales@johndoe.com
Sendmail is not case-sensitive so it sees these as the same alias
- `
/etc/mail/virtusertable`
sales@johndoe.com -> sales
when sales is an actual e-mail address in `/etc/passwd`
AIT’s Linux environment views the alias files after checking the passwd file so each time a request is sent to a user in the passwd file another request is then sent to the alias file (virtusertable) and thus the loop begins.

