I am running sendmail on a Linux Fedora Core 2 machine and I am running into a few problems. Everything is working fine if the users are using IMAP of POP3 with in the facilities(subnets) that I am allowing to relay. However, if users are outside of these subnets, mostly at home or traveling, and they want to check their mail they have problems. They can receive mail just fine, they just cannot send. What do I need to do to fix this.

Also, periodically users get an error when trying to send or receive mail, that states that the server has not replied in 60 seconds. What do I need to look at to start troubleshooting this?

The easy solution would be to put in /etc/mail/access

.com RELAY

(and run the Makefile with make)


But this is a very bad idea in the first place. Because this makes your
mailserver an 'open relay' as anybody will be able to abuse it to send spam.

a possible solution is that you intercept in your facility al outgoing tcp trafic
to a port 25 (expect from you mailserver) and forward it to your mailserver.

for example: (just to give an idea)
iptables -t nat A PREROUTING -s MailServer -p tcp --dport 25 -j ACCEPT
iptables -t nat -A PREROUTING -s insideNetwork -d ! MailServer -p tcp --dport 25 -j DNAT --to-destination MailServer:25

this way any laptop can configure the external smtp server they use outside, and when the are
inside they will use your sever to send mail, without reconfiguring)

The other way is to use authentication and TLS which I never did, but you can probably find
some info about it. Then it is not port 25 anymore that your pc's will use to connect so maybe
you need to change your firewall also.

Tlowk