Question

There are dozen of questions asking is smtp server working like Testing SMTP server is running via C# and Can I test SmtpClient before calling client.Send()? and they do they work of checking by sending commands to smtp servers. They never use any credentials for testing purposes. So I’m wondering is there a way to check are these login and password valid on this smtp-server without sending a mail?

Answer 1

SMTP doesn’t allow you login without sending an email.

have a look at the below:

How to validate smtp credentials before sending mail?