Hi,
I have been having issues sending to some, not all, email addresses from my Thunderbird account. I recieve this message;

An error occurred while sending mail. The mail server responded: "The recipient cannot be verified. Please check all recipients of this message to verify they are valid." Please varify that your email address is correct in your Mail pefrences and try again.

I know my outgoing settings are correct, what else should I be looking for?

Thanks.

Hi Dude

See if this may be of any help.
Cannot send mail - MozillaZine Knowledge Base

Thanks but that is too basic.
My SMTP is correct and I'm not using port 25.