I have setup my Mac to get mail from a UDomain account quite a while back. Since early 2015, Mac Mail started to fail getting mail from the account. I was not sure if the problem was caused by a change from Apple or UDomain. I called UDomain support and they just pointed me to an error message from my Mac saying authentication failed. That was no help. I did not record the Mac Mail version when I start having problem, the current version on my iBook is 9.2.
Recently, I found some time to debug this problem. I found an option in Mac Mail preference dialog that fixed the problem. Here are the steps to apply the fix.
On Mac Mail, select
Mail | Preferences... | <mail account> | Advanced
Then uncheck option
[] Automatically detect and maintain account settings
Let me know if this is helpful.
Poon
2/24/2016
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