I did that after you mentioned MX entries and I had a look around.
I think the problem may be at the registrar (OVH) in the MX servers for the domain I have:
Field Type Configuration Target address
.eisnercomputers.co.uk MX 1 Redirections redirect.ovh.net
.eisnercomputers.co.uk MX 100 Redirections mxb.ovh.net
I'm not sure what these entried actually do but it seems theyre sending my mail on a wild goose chase...
Edit:
I havent tried to receive mail from the primary domain... Its just a subdomain of x10hosting.com but I will try... Could it be a problem with the domain registrar settings I just posted? That would explain why the mail function worked.
Edit:
there is a setting in the MX record on x10's cPanel that says:
Always accept mail locally even if the primary mx does not point to this server.
The checkbox associated with it is checked so I guess that "the primary mx does not point to this server"
Edit:
Just to make this mammoth post complete, these are all the entried under "DNS zone" with my registrar. It seems to include the MX entries. I have not modified any of this, it's all automatic.
Field Type Target address
.eisnercomputers.co.uk NS dns13.ovh.net
.eisnercomputers.co.uk NS ns13.ovh.net
.eisnercomputers.co.uk MX 1 redirect.ovh.net
.eisnercomputers.co.uk MX 100 mxb.ovh.net
.eisnercomputers.co.uk A 213.186.33.5
www.eisnercomputers.co.uk CNAME eisnercomputers.co.uk
audio.eisnercomputers.co.uk CNAME audio.ovh.net
ftp.eisnercomputers.co.uk CNAME eisnercomputers.co.uk
ftp2.eisnercomputers.co.uk CNAME anonymous.ftp.ovh.net
imp.eisnercomputers.co.uk CNAME imp.ovh.net
jabber.eisnercomputers.co.uk CNAME jab1.redirect.ovh.net
mail.eisnercomputers.co.uk CNAME ns0.ovh.net
ox.eisnercomputers.co.uk CNAME ox.ovh.net
pop3.eisnercomputers.co.uk CNAME ns0.ovh.net
sip.eisnercomputers.co.uk CNAME sip1.redirect.ovh.net
smtp.eisnercomputers.co.uk CNAME ns0.ovh.net
squirrel.eisnercomputers.co.uk CNAME squirrel.ovh.net
vpn.eisnercomputers.co.uk CNAME vpn.redirect.ovh.net
.eisnercomputers.co.uk SPF v=spf1 include:mx.ovh.com ~all