I'm trying get a Debian box to act as a mail server. I'm using
exim. Presently, it receives mail, but it won't send mail, at least to
the destinations I've been using for testing.
When it tries to connect to a mail server, the connection is either
refused or just hangs and then times out. Just to test, I also tried
using telnet to connect to port 25 of the same hosts. Same thing: either
"telnet: Unable to connect to remote host: Connection refused" or nothing.
The weird thing is: I think I had it working earlier yesterday, and since
then, I've hardly changed anything...just some rewriting and aliasing
configuration in exim.
On what basis could a mail server decide which hosts it is going to allow
to connect to it?
Thanks for your help.