Mail App Not Working with Self-Signed Certificates

Question

First and foremost, I apologise for starting another thread that is 90% similar to others but I wanted to avoid falling into an existing context.  Like may others, I am having issues with the Mail App in Mavericks but I have an email account other than G-Mail.
That being said, here is the issue I am having.  Until recently I never had an issue sending and receiving email from various accounted.  My Internet provider, an Exchange account, even a G-Mail account.
Yesterday, my Web hosting provider issued a new (self-signed) certificate as the old one had expired (which was also a self-signed certificate).  While I am able to still receive messages, I am no longer able to send any.
I have tried numberous possible solutions to no avail.  I have removed and readded my email account, I have refreshed my SMTP settings, I have removed all semblence of the account from my Key Chain, added the Certificate manually with full trust, and I have even flushed the caches from my ~/Library/ folder.  The last one perked up the Mail App but did not restore my ability to send messages from my Web provider's SMTP server.
I suspect this is a bug in the Mail App but I'm hoping I can find a few last solutions before I file a bug report.
In the meantime, I am using another outgoing server from my Internet provider.  It will do but for consistency I'd much rather use the outgoing server that came with the email account in question.
I am all but convinced it is the Mail App as Thunderbird is able to use the SMTP server just fine and I am still able to send messages using the exact same settings on my iPhone and iPad.
In case it helps, I am using a Early 2011 MacBook Pro with the latest Mavericks update (which ironically was meant to solve some issues other users had with the Mail App).
On a related note, I wish I had stayed on Snow Leopard.  I did not have a single issue with that OS.  Now I feel like I am working on Windows Vista again and I am waiting for the Apple version of Windows 7 to set things right.

Answer 1

MrsCDS wrote:
I am using an iPhone 6 plus on iOS 8.1 and suddenly my Yahoo email account will not populate to my Mail app. I have deleted and re-added the account and also re-booted the phone with no luck. I get the spinning wheel up by my Wi-Fi signal that suggests it's attempting to do something, but the bottom of the Inbox only says "Updated Yesterday." Has anyone else experienced this or can someone, especially an Apple employee, tell me how to fix this?
There is no Apple in this user to user technical forum, if you want an Apple employee you would need to take your phone to the Apple store.
What happens when you switch to using cellular data?  Does your email update?
FYI - Yahoo email account is notoriously bad, you can try their app.