My SMTP server requires me to login before sending any email.

How can I setup this to prevent-
The mail server doesn't like the name zzz@domain.com.
Have you set the recipient address correctly?

The error message indicates that your mail server does not like the recipient address. It does not say you have any login problem.
Hopefuly this answers your question.

: My SMTP server requires me to login before sending any email.

: How can I setup this to prevent-
: The mail server doesn't like the name zzz@domain.com.
: Have you set the recipient address correctly?