Error when testing Outlook connection
Problem reported by Oliver - 3/18/2024 at 4:26 PM

When I run the "Outlook connection" test on https://testconnectivity.microsoft.com/tests/o365, the test is aborted due to an SSL certificate error.

After searching the net, I noticed that SmarterMail creates the Let's Encrypt certificates with ECDSA sigantur.

If I replace these certificates with self-created certificates of type RSA, the test runs without error.

On further searching I noticed that known hosted exchange servers or competitor products run on certificates with RSA.

Can SmarterMail change the Let's Encrypt certificate to RSA signature, or is the only possibility to go the cumbersome way and create the right certificates myself?

Thanks for your answer

2 Replies

Reply to Thread
Douglas Foster Replied
ECDSA is the newer and stronger encryption technique.   Microsoft's test tool is old code.  Consider this a non,-problem.
Oliver Replied
I am aware that ECDSA is newer. Exchange 2016 and 2019 also only run with RSA. As Outlook is a product for Exchange, I do think that problems can occur with MAPI connections.

Reply to Thread