Using Old Email Address

[#1]

I have changed my settings in Outlook Express to show the outgoing server as relay.plus.net and unticked My Server Requires Authentication as shown in the plusnet guide but some emails won't send (error code 0x800CCC79). My old isp was O2. Can someone please help? Thanks.

[#2]

Is there any other information apart from that error code?
Sometimes that error code is caused by the sending or recipient address being invalid.

[#3]

This is the full error message:
The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was joe.bloggs@interternet.com'. Subject 'Enquiry', Account: 'mail.o2.co.uk', Server: 'relay.plus.net', Protocol: SMTP, Server Response: '550 <joe.bloggs@interternet.com> recipient rejected - domain has no delivery address (DNS MX or A record)', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79
Cheers

[#4]

That text says the error arose because the domain part of the recipient's email address (that's the part after the @) is not configured to accept mail. That implies the "to" email address you have supplied is not correct.

[#5]

Thank you. It just seemed especially odd that this was the 2nd email in a row I've had via the same site (we have a company website that forwards emails to me through an enquiry form) that I was unable to reply to. I'll see how I get on this week.