I got the following Bugzilla error when resolving Bug 15660 (email addresses ofuscated)
Apart from teh sendmail error, note that the destination email address shouldn't be getting an email (at least from bugzilla point of view). It is nowhere on the bug (assigned to wikibugs, kooliamdabest the reporter and only me at CC, no votes).

Bug 15660 processed

Changes submitted for bug 15660

Email sent to:
    wikibugs-l@..., kooliamdabest@... 
Excluding:
    Platonides@...

Bugzilla has suffered an internal error. Please save this page and send it to brion@wikimedia.tld with details of what you were doing at the time this message appeared.

URL: https://bugzilla.wikimedia.org/process_bug.cgi
There was an error sending mail from 'bugzilla-daemon@mail.wikimedia.tld' to 'coppertwig@gmail.tld':error when closing pipe to /usr/lib/sendmail:

Version: unspecified
Severity: normal