Projects: Client reply email to forum message is rejected by zoho?

Projects: Client reply email to forum message is rejected by zoho?

I went to the projects module. I then went to the prpject and clicked the forum tab. I added a topic/messge and selected an email notification user.
 
The email gets recived by the client user but when they reply via email zoho rejects the emails and sends this bounce message:
 
--start copy message--
We are unable to post reply to this forum.

WHY DID THIS HAPPEN?
We suspect the below reasons to be the cause of failure :

1. You might have mis-spelt the email address.
2. You might have added the email address in CC or BCC.





--end copy message--
 
The TO field is the same email as shows on the forum at the very bottom. mispellig cannot bethe issue, all the client does is click the reply button in hotmail and the address was not in the cc or bcc field.. it was correct in the to field.
 
I have tried several attemots but the issue is not resolving.
 
If this is resolved. we are defintely settig up with zoho buisiness for our entire oraganization for email and projects. We currently use basecamp and this looks like basecamp with additional features and a nicer interface. Great job. But I need to know my clients can reply to forum posts via email.. it is the most critical feature of all.
 
Any ideas?
 
Don Gerrity
Atomicnorth.com