I have been using SendMail for several months on a weekly basis without any problems. Today I ran the same code and server settings (no changes) and received:
I checked the mail server and it is working for sending smtp mail with a mail client (Thunderbird) using identical settings. Is there any way to see more information about the cause of this error message?
Any help is greatly appreciated.
Apparently there was an issue at the mail hosting service so port numbers changed. It would be nice to see more diagnostic information in the error message.
This post gives a nice alternative to SendMail (for future reference).
I have the same failure when using SendMail ! I tried several changes in the outgoing mail preferences of the desktop.
Receiving mail is working.
I have an extra mailbox (Settings) from my mail provider. I use it only for experimenting with Wolfram Language.
It's very difficult to solve a problem with this error information.