For whatever it's worth, Thunderbird is a simple, standalone email client, totally lacking in intelligence. It sits on your IP address, and it uses the server setup that you provide it. It has no IP address of its own. You might try sending a simple, plain text message, no signature, no graphics, and see if that gets through. For example, your email may have a signature that links to another site.

Thank you so much, David. This helps knowing that there is no IP Address. None of my texts to Zianet.com have a signature, graphics, or anything unusual. It's not just one Zianet address that is being returned, it is all Zianet addresses. No problems with any other email providers, just Zianet. Zianet is local, family-owned, and their tech support has been unable to resolve the issue from their end. It may be in my personal computer set-up. No one else I know of has this issue. Thanks for responding!

Well, I'm not being much help. It's unfortunate that zianet can't give much assistance. There is really nothing you can do in the setup to cause that, as the Earthlink servers have specific IP addresses beyond your control. The only IP address left (that I can think of) is the IP address of your PC. That is provided by your internet provider, not your email provider. There may be others here who have suggestions on tracking down the issue.

Thank you very much, David. I will send my laptop computer information to Zianet tech support. I appreciate your responses very much. Take care.

Jean, does the message that you receive have any more information, e.g., about why sending to the address reaches the maximium number of attempts?

What you have shared so far does not suggest that you as the sender are being blocked (because of association with an IP address). It suggests that the Earthlink server tries repeatedly to deliver the message to Zianet. If an IP address were blocked, Earthlink would try once, receive a rejection, and quit.

Thank you so much, Rick. Here is a copy and paste of the returned email, minus the message and the list of non-zianet recipients:

postmaster@earthlink-vadesecure.net

Delivery has failed to these recipients or distribution lists:

Server "zianet.com" returned an error:

• [hpollard@zianet.com]: message reached max retries

Authentication-Results: earthlink-vadesecure.net; auth=pass smtp.auth=jeanfulton@earthlink.net smtp.mailfrom=jeanfulton@earthlink.net; Received: from [192.168.10.102] ([67.143.180.56]) by vsel1nmtao01p.internal.vadesecure.com with ngmta id 48c82eca-188a1cab439a7dda; Mon, 12 Jan 2026 22:35:32 +0000 Message-ID: <35210bba-27ea-40e6-858d-5d16b6b6d300@earthlink.net> Date: Mon, 12 Jan 2026 15:35:21 -0700 Subject: Potential Consultants: Marketing and Operations Plan (MOP) From: Jean Fulton <jeanfulton@earthlink.net>

Hmm. I don't know. Are you using a VPN? I don't know any reason why an IP address from a VPN server would cause this problem, but that's my only guess.

Thanks for your insight, Rick. I missed that possibility of max sending issue. Since zianet says there is anothier IP address, maybe they could report to the user what it is. I still am concerned that zianet doesn't appear to have the tools to document this. Puzzling.