When opening my Mail application (v9.3 in OS 10.11.6) two pop-ups have to be clicked before I receive messages. They both say: "Mail can't verify the identity of the server 'POP3.toucan.......com". "The certificate for this server is invalid. Would you like to connect to the server anyway?" I click 'Continue' (on both pop-ups) and then Mail works. This procedure works but is slow and I would like to correct it. In Mail Preferences I have three accounts: iCloud-IMAP, POP Account-IMAP, POP Account-POP. I suspect the problem might be the Alias for iCloud is the default and that is the IMAP account type. To edit the alias do I have to go onto the Apple site then change it to the POP Account? Have tried to do this but can't get off iCloud. Help, am going round in circles!
POP and IMAP are alternative types of mail account so "POP Account-IMAP" is a bit odd. I suggest looking at Mail's Preferences, Accounts tab where each account is listed with its name and type. That same tab will tell you the E-Mail address associated with the account and hence the provider. Do you have 3 E-Mail addresses?
If you could feed back that info, it may be possible to check other settings that could be incorrect. An invalid certificate is not something to take too lightly, especially as most of us send personal E-Mail messages sometimes with personal details that we would not wish to go astray.
What makes you think you have an alias for your iCloud address?
Roy Rainford 