Special characters like
&/()=#+
are removed from the user name after saving the chances in the SMTP settings.
Keywords: SMTP settings
Probably same issue we had once with the super user password (due to not htmlencoding or something like this)
(In [5242]) Fixes #2464
morefx, please test this feature when we release Piwik 1.6 RC (in 2 or 3 days) and post a comment if it still doesnt work. thanks!