I just started using gentoo. Love it.
I'm trying to build a web server.
I had some dummy php code that made a call to mail() and noticed I was getting this stderr:
sendmail: 553 <my_hostname>.adelphia.net does not exist

I tracked it down and in my config
sendmail is just a link to ssmtp.
looked at the ssmtp config, and nothing's been edited)
just has

I don't really understand what's going on.

I'm just afraid someone's gotten in my computer and is putting stuff in it or is trying to have it be part of a bot net.
I don't want to overwrite stuff because I really want to find out if someone got inside...

I tried searching for adelphia in various files, but all I know it could be spelled out "a"."d"."e".....

Any help to find where it's retrieving "adelphia.net" from would be appreciated.