I have been having problems with sending out mail, whether over WIFI or cellular. When I tried to look at my errors on my Mac, it told me the SMTP was not available. Sure enough, when I ran Connection Doctor (built into the Mail app) all my SMTP for .mac addresses gave errors and the gmails were OK.
I am posting this on the TidBITS Talk website instead of through the mail, for obvious reasons. Is anyone else seeing this? I tried to edit the Mail SMTP preferences, but that did not seem to work. No errors on Apple’s Status Site.