I would expect Telstra to help more. Apparently, they are using service from Abusix to identify spammers and other bad actors. The message is from Telstra’s server. Telstra must take responsibility for what their server is doing. I would call them again.

If they don’t help, maybe you can deal with Abusix directly. Find out why you were blacklisted and how to get off the list.

You will want to learn how to avoid sending messages that appear to be spam or worse.

Thanks for your reply Rick. I'll certainly be in touch with Telstra again. Cheers, Chris

You appear to e connected to the internet according to that error using origin broadband and trying to send from Telstra. I think that might be the root of the problem. I would not put it past Telstra to require you to connect to the internet using their service to send mails from their server. It has been a popular customer lock-in cojcept in the US for years and Telstra do keep employing US refugees as managers and CEOs so they have probably adopted it.

Tracing route to 103-224-52-151.ipv4.originbroadband.com.au [103.224.52.151]

That IP address does come up as a spam address as well https://www.openreputationapi.com/ip/103.224.52.151

The IP address may also be an endpoint for a VPN, one of the things the advertisements do not mention is you share endpoints with loads of other folk as you rarely use the same one twice and the internet basically ran out of IP V4 addresses sometime ago.

I did check the IP address with my preferred blocklisting service and they did have it listed in December. I would suggest you read the information under the more button in the link before you do a great deal more. https://check.spamhaus.org/results?query=103.224.52.151

It may well be you have more issues than just an email problem.

Thanks for your reply Matt. This seems to be getting more and more convoluted doesn't it? My broadband provider is Origin Energy. It looks as if I'll be communicating with them next. Many thanks for the references you provided. Cheers, Chris

Hello all. Chris here again. I have had no luck resolving my problem. The interesting thing is that when I search for my current IP provider I get a Telstra address which bears no resemblance to the one quoted. I've been trying to contact Abusix direct but they insist on a company name on their question link. Does anybody know of a way to contact them please? It's all very frustrating. Cheers, Chris

I'm sorry that I don't understand the service relationships. Why must you search for your provider? What address is "the one quoted"?

It seemed simple to me: Telstra provides your e-mail service; Telstra's server is preventing you from sending mail; talk again with Telstra.

I'm sorry that I cannot help more. I defer to Matt.

Do you have a VPN? Perhaps as a part of your internet security/Antivirus product of choice.

I simply do not understand how you could have an IP address issued by Telstra if you are not using a VPN and are with Origin Energy. I do not follows these niche broadband providers to me Origin ins an energy provider and nothing more.

SO if you have a VPN that is a recipe for disaster where email is concerned, not only with Telstra, but with just about everyone in the industry. They all have fraud prevention processes running and almost all of them will cause you issues if you use a VPN.

Now to the second issue here. Too quote you original posting

Unable to send emails on Thunderbird I've checked my IMAP settings are they are all correct.

The issue here is IMAP is only for incoming mail and I see no mention of any sort of issue with getting mail. So goto your outgoing server (SMTP) account entry in account settings and check those against the settings Telstra publish. https://www.telstra.com.au/support/email/imap-pop-smtp-mail-server-settings

I have not been an internet customer of Telstra for a number of years. I am stuck with them for phone as they are the only meaningful choice here in the boonies, but I understand they recently retired all of their Bigpond infrastructure. Could you still be using old/ancient Bigpond settings to send mail? Checking the SMTP entries will confirm or disprove that

To Matt and all the kind people who have helped with my problem. I got it fixed today. I went to a local computer shop and it helps to talk to people unlike me who know what they're talking. After trying Telstra again with no success the gentleman at the shop took about 10 minutes to fix it. It tur ned out that Thunderbird didn't recognise the new password that Telstra insisted I change. There were also a couple of other things that needed sorting but the result is that I can now send and receive ok. Thank you all for your help. Cheers, Chris

To Matt and all the kind people who have helped with my problem. I got it fixed today. I went to a local computer shop and it helps to talk to people unlike me who know what they're talking. After trying Telstra again with no success the gentleman at the shop took about 10 minutes to fix it. It tur ned out that Thunderbird didn't recognise the new password that Telstra insisted I change. There were also a couple of other things that needed sorting but the result is that I can now send and receive ok. Thank you all for your help. Cheers, Chris

A password issue would not explain Abusix blocking your sending. Apparently, your address came off a blacklist/blocklist.