I decided to take the plunge on Thursday (1st October 2015) and upgrade OS X to version 10.11 El Capitan. By and large I haven’t noticed much difference and it all seemed to go smoothly.
Alas, there seems to be one particular problem that Apple really need to sort out as a priority. If you use an Exchange server via Apple’s mail app you used to be able to go to Library/Mail/V2/MailData and set up an accounts.plist file so that the ‘From‘ dropdown in OS X Mail would give you a list of email aliases to choose from when sending a message.
The upgrade to El Capitan created a Library/Mail/V3/MailData folder but there was no accounts.plist in there and thus no Exchange mail aliases available via the ‘From‘ dropdown in OSX Mail.
I tried copying the accounts.plist from V2/MailData to V3/Maildata but that doesn’t appear to work and a Google search of the problem has not uncovered a solution.
To make matters worse, Outlook on Office for Mac 2011 seems to hang indefinitely on startup so I can’t even use that for aliases. Microsoft are aware of this but their ‘Workaround’ is laughable.
So, be aware of this issue if you plan going to El Capitan and use Exchange via OS X mail. I’ll post a solution if I find one.
UPDATE: I have now found a solution to this.