send an email with something in it to matt_au@gmx.com and we will see if it arrives.

GMX appear to be less choosy in whom they accept email from.

Just sent an email to you from b*******n@comcast.net. Please don't respond back to that address -- it is my client's address. You can respond back through the forum or email me at the address I included in the body of the email. Thanks!

Are you sure the email came from Thunderbird and not the comcast web interface?

I would have expected the user agent string like the following to appear in the email.

User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0) Gecko/20100101
Thunderbird/60.4.0

What I am seeing is.

X-Originating-Client: open-xchange-appsuite

There is no user agent string in the header at all.

So I am guessing we have proved I can receive email sent from the comcast web mail.

Can I have two this time... one with any signature files usually used and one without. I have a feeling the signature file if there is one will be the problem.

Thanks, Matt. Just sent an email remotely through Thunderbird this time. I don't believe that my client has any signature files. If you see any and they need to be removed, please let me know how I can do that.

and I see no incoming email. Save what was sent as an EML and send it as an attachment using that web interface. Then I can at least see what was not delivered.

Can you post the mail and news accounts information from the troubleshooting information on the help menu (you can drag the mouse over it and Ctrl+C to copy it)

I have so far ignored the anti virus because you said you turned it off. But really we should test the device in Windows safe mode as that eliminates more and some anti virus programs don't turn off when they say they do. Thy even have to be uninstalled with a downloadable uninstaller, not the one that that came with the installations (Symantec here)

The following is really generic basic troubleshooting information

• Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.
• Restart the operating system in safe mode with Networking. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, OSX

If safe mode for the operating system fixes the issue, there's other software in your computer that's causing problems. Possibilities include but not limited to: AV scanning, virus/malware, background downloads such as program updates.

Hi Mike,

I sent you the EML file of the email that did not go thru.

On a happy note, I remoted in and tested T-Bird today. All the emails that I sent went through, and I received incoming ones as well. She has a Comcast email domain, and I noticed yesterday that another client with Comcast was also having issues receiving emails -- in particular from Gmail. Perhaps it was a glithc with Comcast...? So, long story short, I going to treat this issue as resolved for the time-being (so I can save my client some additional money), but if you note anything suspicious in the EML file, please let me know.

Thank you so much!

I will go with that. My guess is Comcast and their weird anti spam filtering was the root cause. As I said in the email it may well have been tumbling over the hyperlink with the mail address as the last thing. Or it might just have been out of control if it "just started working" again.