Keep getting above error messageg. Discused with comcast says it does nor support em client software back in your court
Sometimes that can happen if you are eg: sending a large amount of mail to too many people at a time. Or it can happen if you send email with content that looks suspicious so the mail server can also temporarily blacklist your ip address.
It can also happen if eg: other users who send mail “through the same ISP are sending spam”, or if other users send mail “through the same mail server are sending spam”, so then it affects all users in the same server address ip range.
So if you are not sending bulk mail and not sending mail that might be deemed possibly suspicious, then you need to report that to your ISP and / or also report that to your mail server tech support. They can then advise how to get your Blacklisted IP address fixed.
eM Client carn’t fix that as is an ISP or mail server related issue and not a mail client issue