Can receive but not send emails
I've used Thunderbird on my mac for years, but recently (last week or so) I can't send any emails, but can still receive them. I switched off my Firewall – made no difference. This is the message I get:
Sending of the message failed. An error occurred while sending mail. The mail server responded: Service unavailable; Client host [5.133.19.50] blocked using sbl.spamhaus.org; https://www.spamhaus.org/sbl/query/SBLCSS.
Please check the message recipient
Looks like I'm being blocked, but why? This is just my work email, so causing me a lot of stress as I can't answer my clients and don't want to reply using personal gmail.
I am not techy at all with this stuff, so please keep explanations at the level of what a small child could understand! :)
Thanks so much.
All Replies (2)
Hello
the message means that your mail server is refusing to send your mail because it thinks that you are a baddie. The source of its knowledge is an internet server (spamhaus) providing a service by listing baddies on the internet. So Spamhaus has said to your mail server that your internet physical (not mail !) address (the [5.133....] thing) is owned by a very bad person, and the mail server is obeying what it's administrators have said to it, that is, following the list of baddies by Spamhaus so that it is refusing to do what you want.
If I check your IP address using https://check.spamhaus.org/ it is indeed returning a hit.
Note that this can happen in lot of circonstances that have little to none to do with Thunderbird. The only case where you could be responsible could be if your computer has been taken over by a baddie that is using it to send spam. It's difficult to help you to check on that, the best you should do is to ask a more experimented person to do that for you. Normally if you use an good antivirus and are careful with opening blindly files that are sent to you, you should be clear. If not, try to call on someone experimented with virus checking and cleaning. If the computer is found to be clean, you or a more experimented person can use the page I linked to you to ask for delisting the IP address. Good luck.
Thank you so much for taking time to investigate and for your very helpful reply GP. I love your descriptive word 'baddies'! :D
After looking at a Macworld article it recommended to run Bitdefender which I did and it found about 5 threats. They have been removed now and I am able to send from Thunderbird.
I only have 1 listing on the CSS Blocklist now to do with this that says:
'This IP is making SMTP connections with HELO values that indicate a problem; either malware or a misconfiguration.'
Says something about blocking port 25 to solve it – beyond my google and implementing capabilities. There is an IT guy here today visiting another business that has kindly agreed to look at it, so hopefully that will help.