SSL Handshake Negotiation Fails

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SSL Handshake Negotiation Fails

Post by Broadwood » Mon Aug 13, 2018 12:36 pm

Hi There

I use plesk to run my server and use LetsEncrypt to provide my domains with ssl certificates. I'm using my main domains certificate as my mailenable SSL cert but my SSL connections are failing dut to handshaking negotiation failure. is this because of the LetsEncrypt certificate or is likely to be due to another problem?
Nick Wood

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Re: SSL Handshake Negotiation Fails

Post by njc-paul » Fri Sep 14, 2018 9:12 pm

Hi Nick,

I don’t think this relates to Let’s Encrypt as I have been experiencing the same issue on my MailEnable server with a different certificate provider, I disabled the chat function which seems to have helped also ensuring the user has a name and reply email in the MailEnable user dialogue also seems to have helped, but we do still see the issue.

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Re: SSL Handshake Negotiation Fails

Post by alltheplugs » Thu Oct 25, 2018 4:07 pm

I am experiencing the same or at least similar isssue. Outbound smtp tls handshakes fail on different end points. O some it works fine (gmail as an example) but on other servers it hangs. The logs show starttls and then the connection just hangs until the smtp timeout is reached. I had to disable outbound tls support until the issue is resolved.

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Re: SSL Handshake Negotiation Fails

Post by MailEnable-Ian » Thu Nov 08, 2018 12:22 am


The SMTP debug log file will provide more detail id the handshake is failing and report an error once the connection times out. If you can post up a log snippet it may help further. Are you routing through an external firewall/proxy (I.e. Cisco Firewall running the MailGuard feature)?

Ian Margarone
MailEnable Support

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