Webmail in DMZ can't connect to sendmail SMTP
I currently have a problem setting up a webmail for an (old) existing pop3 mailserver with sendmail. Here are the facts:
The mail server is a Solaris 8 box with sendmail, providing SMTP and POP3, and in the LAN zone.
I've successfully set up the webmail on a test VM in the same LAN zone : Debian, Apache 2, and Afterlogic Webmail Lite. Everything worked fine.
Then, I used an existing Debian server in the DMZ zone to install the webmail.
All the ports forwarding and other firewall configuration are correct.
I'm able to retrieve my mails with the webmail, but I can't send anything since I can't connect to SMTP server.
Obviously, I suspected a mail relaying problem, and added the IP address of the webmail to /etc/mail/relay-domains and /etc/mail/access (then recompiled to access.db) on the sendmail box.
But I'm still not able to send any mails, and I can't telnet the sendmail box on port 25.
Has anyone an idea ?