Help With SendMail Please !

[mattevansnz]

Hi All,

I am quite new to linux.

Sendmail is working perfectly fine when sending to an email address that isnt associated within our company.

For example, an email to a gmail account, it sends fine, but when I test an email to a company email it is never sent.

It isn't getting trapped at the firewall, it doesn't make it that far.

I noticed two things in the maillog it referred to “DSN: Service unavailable” and “dsn=5.0.0, stat=Service unavailable” for the emails that aren't being sent.

Any help would be much appreciated!

Thanks,

Matt.

[Roxoff]

Things to check:

- Check that your domain name is set correctly for your mail server, if it's not then the server will not know what local addresses are. You can force your domain name in your sendmail config if you need to.

- Check that DNS is configured correctly for the server
- if it's using an external DNS server provided by your ISP, make sure that the MX record for your machine's domain points at your mailserver. It could be trying to send the mail using DNS information, which should point back to your server.
- if you've got a local DNS server, make sure the mail server box is using it (set in the network setting or through /etc/resolv.conf) and that the internal mail address is set to the right internal IP address.