Cannot mail from google compute server using monit v5.22 and sendgrid

[Gerard Moroney]

1 Create VM in Google Compute

2 Compile and Install monit v5.22 on centos-release-6-6.el6.centos.12.2.x86_64 server

3 Add following to /etc/monitrc

set mailserver smtp.sendgrid.net port 2525 username "apikey" password "<key>" using TLSV1 with timeout 30 seconds

4 Start monit

5 Following errors seen in /var/log/monit.log

[UTC Jun 6 08:34:32] error : Cannot create socket to [smtp.sendgrid.net]:2525 -- SSL connection error: error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol

[UTC Jun 6 08:34:32] error : Cannot open a connection to the mailserver smtp.sendgrid.net:2525 -- Success

[UTC Jun 6 08:34:32] error : Mail: Delivery failed -- no mail server is available

[UTC Jun 6 08:34:32] error : Aborting event

• I used nc command to check port is open

• I confirmed with Google that port 2525 should be used for outbound smtp

[Tildeslash]

The "using TLSv1" option forces the communication to TLSv1 (connection with SSL handshake), but the "smtp.sendgrid.net" is not SSL/TLS port ... it provides plaintext SMTP service and the client can use STARTTLS to switch to SSL, so the SSL connection ends up with "SSL23_GET_SERVER_HELLO:unknown protocol" (the server doesn't speak SSL):

$ telnet smtp.sendgrid.net 2525
Trying 159.122.224.196...
Connected to smtp.sendgrid.net.
Escape character is '^]'.
220 SG ESMTP service ready at ismtpd0004p1lon1.sendgrid.net

The "using TLSv1" option should be removed from monit configuration.

[Gerard Moroney]

changed configuration as follows:

set mailserver smtp.sendgrid.net port 2525 username "apikey" password "<key>" using STARTTLS with timeout 30 seconds

It works

Issue can be closed. Please excuse my silliness