thanks
if it is of any use, below is the mail I got from my host about it with a copy of their log files - i've replaced addresses with zzz. If you want the 'proper' info I'll pm it.
The mail sent from zzz@zarron.com to zzz@ntlworld.com has been returned with the same 452 error. In the case of all these emails, the mail is physically being sent from our mailserver to NTL, however NTL are rejecting this.
As you are able to send to your NTL account from Yahoo, this would suggest either the zarron.com and electricvenus.com domains are being blocked by NTL, or they have blacklisted the entire server. The error being received does not agree with this however, as blacklisted mail should be returned with a specific error code, rather than an insufficient system storage error.
The following is the log of your mail sent from zzz@zarron.com to your own NTL address, I would suggest passing this on to NTL as they should be able to advise you as to why the email is being blocked, and why it is rejected with an insufficient system storage error.
2004-11-21 20:15:40 1CVy7Y-0000Gk-Nd <= zzz@zarron.com H=cpc4-scun1-3-0-custzzz.nott.cable.ntl.com (monster) [81.103.zzz.152] P=esmtpa A=fixed_login:zzz@zarron.com S=1421 id=LCECJLMJJBNIJDIPABFKKEGLCGAA.zzz@zarron.com
2004-11-21 20:15:42 1CVy7Y-0000Gk-Nd == zzz@ntlworld.com R=lookuphost T=remote_smtp defer (0): SMTP error from remote mailer after end of data: host smtpin.ntlworld.com [212.250.zzz.8]: 452 Message rejected