SMTP problem sending

Is anyone else having problems sending emails using smtp.ntlworld.com ?. Mine was fine (well 99% fine) until week ago. Rang them and seemed to work then for 1 more day but went again yesterday and wont send any emails. One thing, I do NOT use the Virgin email address to send, I use my own domain name/email address and send it via ntlworld.com SMTP That has been fine until now. Maybe they are not allowing users to use their own email addresses ??

Any ideas ?

whats the error message?

In reply to a post by pete_thomson:

whats the error message?

Pete Thanks for message and sorry so long to respond. I didnt record the message but basically it kept coming up with the dialog box for user name and password for smtp but wouldnt accept the correct ones. I then clicked that I had forced an IP change earlier in day by changing the MAC address on my router and restarting. It had worked before that. What I did was change the IP again and it worked. Something to do with that forced IP change ,which I do quite often in fact.

Kia