Dear Maintainer,

   * What led up to the situation?

Configuration of a user with an apostrophe in the username.

   * What exactly did you do (or not do) that was effective (or
     ineffective)?

Generate outgoing email or calendar requests from this user.

   * What was the outcome of this action?

The mail failed with "Unroutable address"

   * What outcome did you expect instead?

Mail/calendar request to be delivered.
------ This is a copy of the message, including all the headers. ------

Return-path: <name.with'@domain.com>
Received: from localhost ([127.0.0.1])
by REDACTED.com with esmtp (Exim 4.80)
(envelope-from <name.with'@domain.com>)
id 1YsplP-000bGK-Mc
for name@domain.com; Thu, 14 May 2015 10:49:14 +0100
x-sogo-message-type: calendar:invitation
MIME-Version: 1.0
content-type: multipart/mixed; boundary="----=_=-_OpenGroupware_org_NGMime-68583-1431596951.570516-9------"
date: Thu, 14 May 2015 09:49:11 +0000
from: "Name With'" <name.with'@domain.com>
subject: Event Invitation: "New Event"
to: "Name With'" <name@domain.com>
Message-Id: <E1YsplP-000bGK-otherperson@domain.com>
X-Spam_score: -0.2
X-Spam_score_int: -1
X-Spam_bar: /

the above is edited to remove personal name of user and system FQDN.

Also reported upstream: http://www.sogo.nu/bugs/view.php?id=3336