At a loss, email failing to send

Question

I am trying to send email from linux (Ubuntu v14), some email addresses it works, and some it's not, and I am completely lost. I am not a linux guy so it's kind of all new to me.

Here's the log from /var/mail/root http://pastebin.com/h4yuA3Rf

I think it might be because I added a MX record for 123reg website because one of the domains wasn't receiving email (or sending, I forget)

Any help would be appreciated

Answer 1

Your DNS is not configured correctly ( no PTR record ) so the other email server thinks you are a spammer and is refusing to accept the mail. Don't use a local MX; use your ISP's instead.