Mac Mail won't send to a particular server

[juiceny]

All of my emails that are sent to a particular server get returned as undeliverable from 5-10 days later. This problem began out of the blue about 2 months ago and it's just one server address that I have the problem with. Of course it's the one I use the most and have about 20 people I need to email to at that address. Does anyone know why this might be happening?

Many thanks.

 

[mkrishnan]

Contact the server operator... sounds like an issue on their side, not on yours. You could have somehow been inadvertently blacklisted as a spammer, for instance.

 

[juiceny]

Mac Mail issue

Thank you for the suggestion. I thought that might be it until I sent mail directly from the optonline webmail server instead of mac mail, and I had no problem doing it that way. Any other thoughts?

Contact the server operator... sounds like an issue on their side, not on yours. You could have somehow been inadvertently blacklisted as a spammer, for instance.

 

[mkrishnan]

Can you explain a little bit more about your setup?

1) Who is your ISP? If your SMTP server is not your ISP's, who runs it?

2) Do you have any other computers that do not use Mail.app (e.g. Outlook on a Windows PC, but not including any webmail services) on the same network that do not have the same problem?

3) Is the webmail service you're referring to the same domain to which you cannot send e-mail, by any chance?

The reason I am asking is because you use a different outgoing system when you use webmail than when you use Mail.app or Outlook. The latter two use an SMTP server (probably for your ISP), while Webmail DOES NOT. So, if for some reason, your mail is being blocked by virtue of your IP address or your ISP being blocked by the recipient's server, it would not affect webmail.