./Maildir: No such file or directory

[fairydust]

I have having problems with my email setup on my server for certain email addresses. I have no problems sending emails to myself and other test email I set-up e.g. hotmail. gmail and my own domain emails.

It works fine for some email address but I get the following email bound back to the adminstration email account for others, with the following error.

./Maildir: No such file or directory

The email that cannot be send definitly has a valid recipient email address. I send emails to it all the time.

Any suggestion as to what the issue is?

Here is the content of the bounce back email with recipient, admin hosting site and Ip changed:

Hi. This is the qmail-send program at My Hosting Site
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

<recipient@example.com>:
./Maildir: No such file or directory

--- Below this line is a copy of the message.

Return-Path: <admin@example.com>
Received: (qmail 3938 invoked from network); 29 Mar 2009 21:14:58 +0100
Received: from MY Hosting Site (HELO My Mail Server) (*.*.*.*)
by My Hosting Site with SMTP; 29 Mar 2009 21:14:58 +0100
Date: Sun, 29 Mar 2009 20:14:58 +0000
To: recipient@example.com
From: "Admin" <admin@example.com>
Auto-Submitted: auto-generated
Message-ID: <20090329201430.3b82e8787806@www.example.ie>
MIME-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 8bit
X-Priority: 3
X-Mailer: vBulletin Mail via PHP
Subject: **subject here**

**Content Here