Strange - error number 0x800ccc79

[Luminance]

I have Outlook 2000, and I can send emails to all of my contacts with no problems at all, but if someone requests a "read receipt", the read report goes to my outbox and cannot be sent. I get the following error:
550 relaying mail to ****.com is not allowed - - - - error number 0x800ccc79
If I then open the read receipt and re-forward it, it goes with no problem. Is it my settings, NTL, or Outlook?

Andy

[Millay]

You may find the answer is to do with authentication.

Go into your account settings and ensure, that 'my outging mail server requires authentication' is ticked.

That might sort it.

[Luminance]

Thanks, I'll try that

Andy

[BarFly]

im pretty sure its because of the new spam filters on NTL's side, because the read receipt is trying to be sent on a ntl connection, but from a non ntl source, the original sender. The smtp server wont allow it to be sent,which is why your getting the relaying error... but when you fwd it back, you are sending from an NTL account which means it goes through all ok...
prepared to be wrong on that though....

there is another thread on this from a while back & someone found a workaround if i remember correctly, have a search....

[simbr]

When Outlook sends read receipts it uses a null sender (<>), and the ntl mail servers reject email that does not have a valid sender.