Collectives™ on Stack Overflow

Find centralized, trusted content and collaborate around the technologies you use most.

Teams

Q&A for work

Connect and share knowledge within a single location that is structured and easy to search.

I am trying to use a free SMTP relay from SendGrid to send emails from my ASP.NET application. I can connect to the server, but when I try to authenticate, I get this error : "The SMTP server has unexpectedly disconnected."

using (var client = new SmtpClient())
            client.ServerCertificateValidationCallback =
                (sender, certificate, certChainType, errors) => true;
            client.AuthenticationMechanisms.Remove("XOAUTH2");
            // connection
            client.Connect("smtp.host", 465, true);
            client.Authenticate("UserName", "Password");//error occurs here
            client.Send(email);
            client.Disconnect(true);
Once again, I can connect without any problem, but when I try to authenticate, I get the previously mentionned error... 
Any suggestions?
Cheers
                That's not quite what I need since I'm using Mailkit. I'm starting to think that maybe SendGrid isn't the most appropriate service for what I'm trying to do.
– jabir saidi
                Aug 27, 2019 at 14:35
Username: is apikey (as a hard-coded value 'apikey').
Password: is the apikey you generated from the web, which is a big hashy-like string.
You can find this on their docs. But it was hard to find.
                And unlike the Telnet example on their site you don't need to Base64 encode either username or API key.
– Alan B
                Apr 21, 2021 at 13:57
I solved my issue changing from SendGrid to gooogle's free SMTP service for all of their users. Simply follow the steps here
and you should be good to go!
        
Thanks for contributing an answer to Stack Overflow!
Please be sure to answer the question. Provide details and share your research!
But avoid …
Asking for help, clarification, or responding to other answers.
Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.