mail-notification does not support umlauts in passwords

Here's the log (private data anonymized):

** INFO: <email address hidden>@pop.gmx.de: pop.gmx.de wird kontaktiert
** INFO: <email address hidden>@pop.gmx.de: Verbindung mit
pop.gmx.de (213.165.64.22) über Port 110 wird hergestellt
** INFO: <email address hidden>@pop.gmx.de: Verbindung hergestellt
** INFO: <email address hidden>@pop.gmx.de: < +OK GMX POP3
StreamProxy ready <15864.1221925614@mp030>
** INFO: <email address hidden>@pop.gmx.de: > CAPA
** INFO: <email address hidden>@pop.gmx.de: < +OK
** INFO: <email address hidden>@pop.gmx.de: < TOP
** INFO: <email address hidden>@pop.gmx.de: < USER
** INFO: <email address hidden>@pop.gmx.de: < SASL LOGIN CRAM-MD5
** INFO: <email address hidden>@pop.gmx.de: < UIDL
** INFO: <email address hidden>@pop.gmx.de: < RESP-CODES
** INFO: <email address hidden>@pop.gmx.de: < .
** INFO: <email address hidden>@pop.gmx.de: > AUTH CRAM-MD5
** INFO: <email address hidden>@pop.gmx.de: < + *challenge deleted
from log*
** INFO: <email address hidden>@pop.gmx.de: > *response deleted from
log*
** INFO: <email address hidden>@pop.gmx.de: < -ERR Authentication
failed.
** INFO: <email address hidden>@pop.gmx.de: Mechanismus CRAM-MD5
wird deaktiviert und SASL-Authentifizierung wird erneut probiert

** (mail-notification:5254): WARNING **:
<email address hidden>@pop.gmx.de: Die SASL-Authentifizierung konnte
nicht gestartet werden: SASL(-4): no mechanism available: No worthy
mechs found
** INFO: <email address hidden>@pop.gmx.de: Es wird auf
Authentifizierung mit APOP zurück gegriffen.
** INFO: <email address hidden>@pop.gmx.de: > APOP
<email address hidden> *deleted from log*
** INFO: <email address hidden>@pop.gmx.de: < -ERR Authentication
failed.
** INFO: <email address hidden>@pop.gmx.de: Es wird auf
Authentifizierung per Nutzername und Passwort zurück gegriffen.
** INFO: <email address hidden>@pop.gmx.de: > USER
<email address hidden>
** INFO: <email address hidden>@pop.gmx.de: < +OK May I have your
password, please?
** INFO: <email address hidden>@pop.gmx.de: > PASS xxxxxäxxxxx
** INFO: <email address hidden>@pop.gmx.de: < -ERR Username or
password incorrect.
** INFO: <email address hidden>@pop.gmx.de: > QUIT
** INFO: <email address hidden>@pop.gmx.de hat einen Fehler erzeugt:
Authentifizierung fehlgeschlagen

Thank you for taking the time to report this bug and helping to make Ubuntu better. We are sorry that we do not always have the capacity to look at all reported bugs in a timely manner. There have been many changes in Ubuntu since that time you reported the bug and your problem may have been fixed with some of the updates. It would help us a lot if you could test it on a currently supported Ubuntu version. When you test it and it is still an issue, kindly upload the updated logs by running apport-collect 272505 and any other logs that are relevant for this particular issue.