Noticed just a couple NDR's from Microsoft EOP recently with a rejection reason: 454 4.7.0 Connection is not TLS encrypted. Recipient organization requires TLS.
What might be causing this?
Connection is not TLS encrypted. Recipient organization requires TLS.
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Re: Connection is not TLS encrypted. Recipient organization requires TLS.
Make sure you are sending over TLS, by checking that the option to send over TLS is enabled under the SMTP outbound settings:
https://www.mailenable.com/documentation/10.0/Enterprise/SMTP_props_Outbound.html
There are various reasons why it may not connect over TLS, such as TLS version compatibility, relaying through another server, etc. You could check the SMTP Activity log for the error message and see if the conversation did use STARTTLS and whether there was an error doing this.
https://www.mailenable.com/documentation/10.0/Enterprise/SMTP_props_Outbound.html
There are various reasons why it may not connect over TLS, such as TLS version compatibility, relaying through another server, etc. You could check the SMTP Activity log for the error message and see if the conversation did use STARTTLS and whether there was an error doing this.
Re: Connection is not TLS encrypted. Recipient organization requires TLS.
I unchecked and rechecked it, then restarted smtp services and have not seen this error since. Perhaps it was an error on the other server all along. I know o365 has been having a lot of issues lately.
