How to Test an SMTP Server with Telnet command line How to test SMTP and IMAP servers using the telnet command-line Linux Networking Windows
Test IMAP with telnet IMAP connection theory The first thing any client needs to do is to make a connection to the remote imap server on a specific port. These ports can vary, but default port for plaintext imap service is 143 , and for encrypted (SSL/TLS) imap service is default port 993 . You can use for plaintext imap connection a telnet utility, or for encrypted imap service you can use openssl s_client command. Networking Linux
