I have some e-mail on my Exchange Queue for 3/4 domains that just won't send. It just says "SMTP Protocol Error Occurred". I activated logging in MSExchangeTransport ...

I'm writing a program that will have to send mail through SMTP. Doing that, I came across a really weid behavior of our exchange 2013 server: If the SMTP session authenticates the session through AUTH ...

Some Outlook users have reported that they are unable to send email from the app as when doing the same, they receive Error 503 stating that the Valid RCPT command ...

Desktop clients send email over Gmail using the simple mail transfer protocol. You can use the telnet program on your computer to connect to Gmail's SMTP server and verify the connection is working ...