A user reported that email was not working. So I logged into an account on the CentOS 7 email server and connected to port 25, the Simple Mail Transport Protocol (SMTP) port, via Telnet to ensure that the server was responding to SMTP connections.
$ telnet 127.0.0.1 25 Trying 127.0.0.1... Connected to 127.0.0.1. Escape character is '^]'. 220 moonpoint.com ESMTP Sendmail 8.14.7/8.14.7; Sat, 6 Aug 2016 09:26:06 -0400 quit 221 2.0.0 moonpoint.com closing connection Connection closed by foreign host. $
Since the
Sendmail SMTP service seemed to be functioning properly, I next checked
the
Dovecot POP3/POP3S software on the system. I entered the commands
an email client would submit to authenticate with the server on the POP3 port,
port 110, i.e., pass followed by the user's login id then
pass and the password for the user's account. I received an
immediate response to the user command, but when I entered
the pass command followed by the password and hit Enter
I didn't see any response even after waiting much longer than I would expect
to have to wait for a response. So I hit Ctrl-], i.e., the Ctrl
and ] keys to return to the Telnet prompt and then exited from
the telnet program.
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