I'm currently using posftix on my ubuntu server to send out emails from a shopping cart system for clients. The only problem is getting the emails to send properly. Mails get through to hotmail fine, gmail detects them as spam, and they aren't getting through to any paid email account. Code: Jul 31 13:09:53 localhost sm-mta: k6V39p8Y017376: to=<[email protected]>, ctladdr=<[email protected]> (33/33), delay=00:00:02, xdelay=00:00:02, mailer=esmtp, pri=121348, relay=mail-fwd.mx.ssggrp-wc.com. [18.104.22.168], dsn=5.0.0, stat=Service unavailable Jul 31 13:09:57 localhost sm-mta: k6V39p8Y017376: k6V39v8Y017378: DSN: Service unavailable Edit: I fixed the name servers up, and now it's just this singular issue, DSN: Service unavailable. I know it could be a number of things, I just need an idea of the things I need to take care of for this to start working properly. Thank you kindly, I will contribute to this forum however I can.