Mail on iMac not sending or receiving emails from ISP server

RichardSRussell wrote:

TDS Telecom, known to the Internet as tds.net. It's a subsidiary of Telephone and Data Systems, Inc. I can see their corporate headquarters from my back porch.

Have you seen this help link on their support site https://tdstelecom.com/support/email/account-configuration-mac.html

Also are you using a VPN? If so turn it off or delete it.

RichardSRussell wrote:

I have a 2019 Intel-based 27" iMac running MacOS Sequoia 15.7.3 and have Mail 16.0 installed. It had been connected to my ISP's mail server, but about 2 weeks ago it stopped being able to send mail, and now it no longer receives mail. How can I go about reconnecting it to the ISP's mail server for both functions? (I'm not real tech savvy, so don't be afraid to talk down to me, and pictures would really help a lot.)

see if this helps If you can’t send or receive email on Mac - Apple Support

Have you contact your ISP support?

RichardSRussell wrote:

I'm able to read and write e-mail using my web browser to access my ISP's gawdawful browser-based user interface, so I'm sure that my internet connection is OK. And I've messaged my ISP pleading for help from their end, but I figured I'd try to cover all my bases by asking for help from the Apple end as well. I wasn't kidding about needing step-by-step instructions for how to link to my ISP's e-mail server.

Who is your ISP provider?