Email not received after TLS 1.0 Disablement .

Last Updated -

Check your mail servers SSL certificate

Your mail server may be set up to utilize TLS v 1.1 or TLS  v1.2. However, you also need to make sure that the installed mail server certificates are also set up to utilize this protocol.

On a mac:
You will need to go to Applications->Utilities ->Terminal and run this command at the terminal:
openssl s_client -showcerts -connect (where "" is your mail server or host) .

For example:
openssl s_client -showcerts -connect

You should see the Protocol showing TLSv1.1 or TLSv1.2 as shown below. If it shows anything else such as TLSv1, then you will need to update your mail servers certificates to allow the proper protocol.

On Windows (also works on mac):
Go to Input your mail server in the field on the form and click "Check it".

In the result you will see the SSL Version being used by your certificate.

You will need to have your IT team or mail host review these results and make the appropriate adjustments to the certificates on their mail server.

If you are using Microsoft Exchange 2010.
Please make sure that you have applied SP3 Rollup 9 per this Technet article.

This should help you to resolve your mail flow issue.

Important note as of 3/7/18 regarding customers using Microsoft Exchange 2010/2013  hosted or in house environments, including Intermedia /

If you use Microsoft Exchange 2010 or 2013 as your IMAP mail server to receive emails in,  please review this Microsoft Technet Article. 

We have had some reports of  with mail servers on  Microsoft 2010/2013 environments not receiving email as they continue to have their SSL defaulting back to TLS 1.0. on requests sent from since disabling TLS 1.0 at 2PM PT on February 28.

The cause of the issue is that on Microsoft Exchange 2010/2013 , TLS 1.0 is the only option for IMAP with TLS connections. You will need to upgrade to Exchange 2016. Intermedia specifically support TLS 1.1 and 1.2 starting from Exchange 2016 based on their findings Technet article. if you do use their service, their support team recommend that you perform an in place upgrade to their Exchange 2016 environments based on this KB Article from their site as you may currently be on an environment that only support TLS 1.0 which is no longer supported by

If you or your mail hosting company use Microsoft Exchange 2010/2013 and cannot resolve the issue using these instructions, we recommend that you work with your IT or support team to have your emails forwarded to your default (Postmark address).

You will need to make sure that your Postmark mailbox is created and enabled in AdminChannelsEmailInbound Mail . Once it is enabled please see  How Do I Forward My Email?  in this article  for instructions on forwarding email to your Postmark mailbox. 

One forwarding is set up, you will need to manually forward all emails that were missed since TLS 1.0 was disabled by  on 2/28/28 at 2PM PT.

If you need help in adjusting rules, filters or any other part of your workflows related to this issue, please reach out to your support team at