When I send an email message to a group, replies from those with “Yahoo” addresses bounce back to senders. This only happens when the those with “Yahoo” addresses are part of a group, not when they are individual recipients.
Sorry to hear about your problem. I went ahead and created a test email account on your server to see if I could replicate the problem. I have a Yahoo email address that I included as part of a group and it delivers with no problem. I also did not see any bounces on the server concerning your emails. If Yahoo is blocking the email, then they may need to consult with Yahoo's support or white list you so you're not getting blocked. The group email should make no difference as it will typically use the individual email addresses to be sent. If you are getting a bounceback email, then can you please provide a copy of it? The bounceback will normally indicate the actual issue. At this point, based on the information you have provided, I am unable to duplicate the problem. I did notice that your email came in as spam on my Yahoo account. It's possible that your domain is being blocked by Yahoo's spam filtering. You can also try using this tool to parse your email bounce. There's also a video explaining the bounces.
I hope this helps to provide a little clarity on the issue. Provide us a copy of the bounce and we can definitely look into the issue in more depth.
Here is a bounce back:
Remote host said: 550 http://www.spamcop.net/bl.shtml?18.104.22.168" [RCPT_TO]
Thanks for the response. I edited your comment so that the entire bounceback is not showing, but we made a copy of it so that we could look at it first. The bounceback indicates that the email is being identified as SPAM by SpamCop. If you look at the bounceback, the beginning of the email gives you a URL for further information:
The IP is being identified as being a source of spam and has been blocked by SpamCopy. You can go to that URL and then look at the information provided. The IP address in question is not coming from Web Hosting Hub. You will need to contact Yahoo with this information so that they can go through the process of de-listing their server.
Apologies again for the problem. In this case the server will need to be delisted from Yahoo's side as it has been identified as a source of spam and blacklisted.