Email for 3rd Party Domain No Longer Able To Send Via Apple Mail Client

Now the Web Hosting Service for my domain says it has nothing to do with settings.

Now they say it's about ciphers and protocols.

They explain it like this: The reason I'm suddenly unable to send third-party emails via IMAP and SMTP on Port 465 using my Apple Mail client is because Apple Mail is no longer capable of connecting to the new modern ciphers that were recently installed on the servers managed by my web hosting service.

According to the hosting service, the problem has nothing to do with the many changes their techs have advised me to make during the prior two weeks. Not my Apple Mail client settings, or Network settings, or AEBS firewall settings, or Motorola DSL modem settings, etc… They apologized for the confusion, and stated definitively that the problem cannot be solved with settings. It requires a different mail client, i.e., not Apple Mail.

They say this was partly due to Apple's decision to snub OpenSSL in favor of Apple's own TLS and crypto libraries. As a result, they say, even the most up-to-date Apple Mail versions will no longer be able to connect to third-party servers that employ these modern ciphers and OpenSSL.

To further support this explanation, my web hosting service cites the Linux-based web-hosting control panel they employ — cPanel — and its effort to improve security by doing away with older ciphers and changing their default server configurations to use only modern ciphers, which are incapable of connecting to Apple Mail. I assume this means all hosting services that employ cPanel will soon yield the same result for customers who use the Apple Mail client, so I expect I may be the first of many seeking answers to these same questions.

I'm just a writer who uses a computer, not a programer, tech or engineer. So, please, if you are someone who can confirm or dismiss this "Open SSL/Modern Ciphers" theory, please do so.

I admit to being inclined to accept this explanation, though at the same time part of me hopes it's wrong because of my affection for the amazing piece of Apple software that we call Mail. Though it may be under-appreciated, and/or under-rated, it is certainly not under-utilized by Apple users like myself.

Furthermore, if true, I expect this will mean we all have to choose between switching to hosting services that utilize Apple's TLS, or finding other Mac-friendly email clients (do those even exist?).

Personally, if it comes down it, I'll chuck the web hosting service a thousand times before I surrender my Apple Mail client, but I'd like to confirm that there's absolutely no other fix before I go to all that trouble.

When it comes to fixing this problem, even the advice of customer support techs has proven untrustworthy. My new mantra is "verify, verify, verify" before making any more changes to settings. In the past 14 days, multiple customer service reps from my web hosting service have given me at least half a dozen different explanations, and fixes, for this problem, only to have them all contradicted by this "OpenSSL/modern cipher" theory. While I appreciate the apology I received from my web hosting service for those errors, I remain skeptical of their explanations and advice. (I'm intentionally not naming the hosting service because this isn't about shaming them, but rather about solving this problem)

By way of attribution for their explanation, my web hosting service directed me to a forum thread for the Cpanel security changes involving modern ciphers and OpenSSL. This thread discusses how the very same problem has been reported on even up-to-date mail clients — including users of Outlook 2016 and Windows 10. These users have experienced the exact same problem as me. Without apparent cause, they were suddenly unable to send third-party emails using previously reliable email clients, and, according to this thread, it's all because of new ciphers and protocols installed by their web hosting services.

Please feel free to confirm, clarify, or dismiss any or all of this. As I stated previously in this post, I'm looking for the true explanation, not the one I want to hear.

Thank you to Eric Root and rccharles for replying to this post and attempting to help me find that explanation.

Everything works now.

The Solution: Update from OS Yosemite 10.10.5 to OS High Sierra, 10.13.5, using Apple Mail Version 11.4 (3445.8.2).

The older version of Mail was cause of the problem.

Thanks again, Eric.

Tried that. Didn't work. But thanks for the suggestion.

The solution is no solution, unfortunately.

Turns out it's got nothing to do with settings at all.

Apple is

This was an incomplete post reply to rccharles and, unfortunately, I'm unable to delete it … please see the full reply post at this link.