If you want to become a developer you have to learn to DEBUG! Did you try to print the list of authentication protocols you obtained from QueryAuthProtocols()? What did you get? Do you have any idea which one did you end up using? Is there anything in the docs about that protocol then? Like for example whether it is supported by Mail::Sender or whether you need to install something for it to be supported? Are you really sure the username and password is correct? Does the message change if you change it to something that's definitely wrong? Does it change if you include the domain\ in front of the username? ...

We can't debug your program for you! We don't have the address of the mail server nor the username and password. Besides you HAVE TO LEARN to debug yourself.

1) I printed the list of authentication protocols which is NTLM GSSAPI LOGIN 2) I am using LOGIN protocol for authentication which is supported by Mail::Sender. 3) username and password is correct because i can send emails without authentication. 4) whatever I am changing which is wrong it says Cannot send mail: Login not accepted

If you can send emails without authentication, why do you attempt to authenticate? And how does the correctness of the username and pwd relate to the fact that you can send emails without using them?

Jenda
Enoch was right!
Enjoy the last years of Rome.

Nowhere. All you do is install the modules.

I only add use Authen::SASL; in my code. and when i run this code it gives me msg Cannot send mail: Login not accepted

Not suprising. You just copied the SYNOPSIS from Mail::Sender. Maybe you wish to spend a little time reading Mail::Sender documentation? Maybe turn on debug?