Inconsistent mail redirect between old and new mail addresses

[ChrisUKC]

I have 5 existing mail names on my domain. All are set for redirect and operate correctly.
However if I add a new mail name and set it the same it will not redirect. The mail sender gets a timeout message.
I have recently taken over running the domain on a Webfusion VPS. Fedora Core2. I think the working mail names were present before the upgrade to 7.5.4. so my suspicion is it is related to that.
We have a forum running on the domain and email handling for registrations etc. is fine.

I've been trawling through the posts and knowledgebase and all seems OK according to what I've found. However most problems are with mail not working, or delayed, not working for some names and not others.

I cannot get into webmail(Horde). I get 'Login Failed' for any mail name, old or new.

I'm learning fast, but I'm in no way a Linux expert.

Chris

 

[ChrisUKC]

Further investigation shows it is all mail addresses when sent to external to the domain. i.e. mail generated by the forum is going out OK, and is redirecting to external addresses OK. That was confusing me.
If I send a mail from an external domain (my home email) it does not redirect and eventually I get a timeout message from my ISP.

Any ideas?