I'm having problem with sending mail via SMTP where the error is username and password does not match, even though they are most certainly correct as the IMAP works. My host wants me to try to uncheck "Automatically detect and maintain account settings" that I access through Mail > Preferences > Accounts, but that checkbox is greyed out and cannot be changed. How can I enable this checkbox?
This is in Yosemite, my email host is Zoho.
Thanks!

