Bit of a strange one. We had to change mail server hosts due to an upgrade. This was an ISP host change and the email address has not changed. The email was off line for a day and then we were told it all is now working. The email is IMAP and SMTP over SSL. Previously this worked fine on my macbook pro, outlook 2010 on the PC and iPhone. After being told today that it is all up and running, I set it up on all three. It works perfectly on outlook and the iPhone. It works for reading email on the apple mail, but the apple mail refuses to send any emails. I've checked the settings about a dozen times, clear the keychain for the email. deleted the SMTP server and added a new one. It refuses to send. According to connection doctor ir failed to get a response from port 465. The PC and iPhone are both on the same local network have the same IMAP/SMTP set up (on port 465) and work perfectly. What is wrong with the apple mail? Apple mail version 7.3, OSX 10.9.5.