And finally I have to open a thread for this. Tried my best to get this working but it just won't. I will try to make it as simple and clear as possible.

We have an shared Inbox which we use to manage internal work. Its shared with two others besides me. So I have this share accepted and inbox is safe in web client. The problem is when I try to reply to a mail in it ('on behalf of') from my inbox, it fails with this error

Permission denied.
method: SendMsgRequest
msg: permission denied: you do not have sufficient permissions
code: service.PERM_DENIED
detail: soap:Sender
trace: com.zimbra.common.service.ServiceException: permission denied:

I have no clue what's happening cause the other two accounts manage the share with no problems. They can reply mails. It is just me that doesn't have permissions on this Inbox. I've been given Admin privilege on it, so it should be plenty.

Surprisingly I have another share accepted and safe in my inbox, I can reply to those mails 'on behalf of' with no issues at all! Bowled.

I've confirmed the option 'Allow sending email from any address' is enabled for my account under sending mails section in zimbraAdmin. Why I can reply mails in some shared Inbox and not others .. So i guess there's a missing bit somewhere. Someone make me happy pls.