This is a server-side error message, indicating that your email provider has, for whatever reason, blocked you from sending email. It could be that they wrongly or rightly think you have been abusing the service by sending out spam, or it could be a temporary problem on their end. There's nothing you can do on your end except contact them to see what's going on.

Thank you for your rapid reply. Email provider has its own webmail client. All works fine using that, but now tith TBird. I really like TBird. Is there anything you can think of that might solve this?

No, it can only be resolved on their end. It's your personal IP address that's blocked. When you use their web mail interface, the mail server interacts with their web server, not your home address.

It may go away on its own if there's a general server problem. If you feel like you've waited long enough, you must contact them for resolution.

If you use a VPN, that could very well be the issue. If so, can you disable it as a test?

Your computer is a different IP that your email provider. This URL looks of possible use, so I share it here: https://www.suped.com/knowledge/email-deliverability/sender-reputation/how-to-resolve-blacklisted-by-internal-reputation-service-email-bounces-from-small-isps Thunderbird itself is not the issue.

To Lin, I hadn't thouht about disabling my VPN, so did that and restarted TBird. Still no luck...same message.

To David, Thank you for providing the information. Today is Sunday and Easter to boot! My service provider usually has a skeleton crew on the weekends, so won't be able to contact them until tomorrow at the earliest.

Thank you both for your help.

Hello David. I'm not tech savvy enough to find the IP address for either my mail system nor the ISP's IP address. I looked in TBird for it, but no luck. Also, don't have a clue where/how to look for the ISP IP address.

Okay, I also am no IP guru, so I use https://ipchicken.com/ to tell me my IP address. :) I suggest working with your email provider to work through this.

The blacklisted IP address is given in the error message: 73.62.119.4. It is on the Spamhaus ZEN black list.

I thought that blacklisted IP addresses were those of servers. Several times, I have been unable to send mail because I used a shared server on a hosting service and someone else on that server was spamming. That would explain why disabling your VPN did not help. But Lin probably knows better than I do that it is indeed your own IP address.

In any case, I agree with Lin and David that probably all you can do is contact your e-mail service provider for help.

The site that david mentioned will tell you the IP address that the outside world, including your email service, sees. It's probably the one mentioned in your first post, "73.62.119.4". There are lots of other similar sites - just Google "what is my ip address". But that information is of little practical use to us users, although if you're going to contact your email provider, they may want to know it (but they can probably look it up on their end or glean it from the error message.)

I see that that IP address belongs to Comcast. If that's who you need to contact, all I can say is, Good luck! They can be a real pain to deal with, especially if your issue doesn't fit neatly into their front-line support's scripts.

Hey Rick. Thanks for the info. Will try again to contact my mail provider's support.

I think the obvious is being missed here.

Comcast do not do their own mail, Yahoo do it for them and 73.62.119.4 is listed in the spamhaus blocklist because it is a residential address (not a mail server) so the mail server is refusing to accept mail from that address.

There are fundamentally only two reasons that mail submitted will be rejected for this reason.

one is that you are not using the correct SMTP server settings. Probably the port. Port 25 is used for relaying email messages from server to server, port 587 is the default SMTP port for message submissions although I understand Xfinity used to also accept submissions on 465. When a mail client submits messages to your email server, that client typically connects via port 587 or 465. So first up check you are not using port 25.

Then as Comcast/Xfinity are migrating everyone to Yahoo, check if this has been offered and completed ad if completed you are using the new correct settings See https://www.xfinity.com/support/articles/yahoo-email-migration-overview

Yahoo also offer information here https://help.yahoo.com/kb/new-yahoo-mail/SLN36803.html

Yahoo state the outgoing settings as https://help.yahoo.com/kb/new-yahoo-mail/SLN36803.html Server: smtp.mail.yahoo.com Port: 465 or 587 Requires SSL: Yes Requires TLS: Yes (if available) Requires authentication: Yes

Note that translates to connection security SSL/TLS in Thunderbird with connection method oAuth2 with the server and ports mentioned.

SO I think you best check your setting in Thunderbird's account settings> outgoing server(SMTP) before moving on at all.

The transition from Comcast's in-house mail service is still rolling out. They say they will give us plenty of advance notice. I haven't gotten the "invitation" yet and my service keeps on rollin'. In fact, I don't know anybody who has gotten a notice/invitation or been told/asked to transition. I haven't heard anything more about it for a few months.

The whole thing is confusing. The Xfinity article you cite above implies to me that the Yahoo switch is not even required! And that if we don't start the process, we will continue to use the old system. Yet I have been told otherwise, that once they tell you, ya gotta:

"Do I have to upgrade my comcast dot net email account to Yahoo Mail?"

No, this is an upgrade we are offering customers at no cost so they can access their email on a better platform with enhanced security, more features, and a mobile app for easy access on the go.

Whatever, once this thing gets going, if it hasn't already, it's bound to create much chaos and confusion.

Hello Matt, Thanks for your info. I've checked my SMTP settings as you suggested. Am using port 465 and security SSL/TLS. However, I could not find connection method oAuth2 so don't know if I have it or not.

All ya'll are correct when it comes to Comcast being miserable to work with, especially tech support. And what do tell you is sometimes errorenous on its face! Non-tech support is even more difficult to work with. If there was any other alternative to Comcast/Xfinity, I would switch in a heartbeat. But they are the only game in town where I currently located.

I can successfully send msgs using my mail provider's webmail, so am contemplating using TBird for inbound mail and webmail for outbbound. Not the ideal solution, nor the one I want to use but I get more and more confused about how to fix and whom to contact. Now it seems Comcast may or may not be the contact, but I don't use their mail system anyway. Or, it seems like Yahoo may or may not be somehow involved. Also it seems as though it is out of my hands and not something I CAN fix!

gotta chew on all of the info you and your colleagues have sent. Unfortunately, April is my really busy month of the year so may not be able to get to digesting all of this stuff for a bit.

Again, thank you all.

If there was any other alternative to Comcast/Xfinity, I would switch in a heartbeat. But they are the only game in town where I currently located.

Comcast may have a local monopoly in internet service and cable TV, but there are many alternatives for e-mail service.

Rick makes a good point. ISPs are known to give the worst email service; that's not really where their business is.