Hi,

why do you think it has to deal witrh TB? Do you receive a response, telling you that the e-mail is classified as spam? Then pls. post this responses content here.

regards georg

im not entirely sure it has to do with TB. i just want to rule out TB as an issue.

i have checked various blacklists, and we are on them. one of these lists, which is SpamHaus, (not really a blacklist) has stated they have a problem with our SMTP authentication. it says its not enabled. our smtp is enabled and we have an smtp server that mail goes out on.

this is the spamhaus link where we found the smtp issue:

http://www.spamhaus.org/pbl/query/PBL1544282

Thanks for your help.

We don't have any responses from Yahoo themselves saying we are spam. We just have noticed that all (and I mean all) of our emails to our customers using yahoo aren't receiving them.

If you are blacklsted you have to work with your provider to fix it. As for Thunderbird, it just sends what you compose. It does not create spam. Users do.

Yahoo only checks against this blacklist probably. Normally the blacklisting is canceled after some hours. There may be a chance, that you can use another mail-server meanwhile for your outgoing mail, which is not on the list to circumvent the problem. As Airmail proposed you should contact your provider for help.

Okay. Thanks much!

the IP block is on 13 blacklist per this lot. http://cqcounter.com/rbl_check/

My guess is that it is a block of IP addresses that have been notified by shaw (the registered IP address owner) as dynamic and there not hosting a mail server. You do not provide your domain name, but it is highly probable that the MX record for the domain is not set correctly (gets people all the time as it is one of the non automatic ones)

The few IP addresses I did check all resolved to shaw routers.

So my guess is you have an on premises mail server connected to a shaw cable dynamic IP address. if you must use dynamic IP addresses from shaw the services of a dynamic DNS service are what you require.