If you find a problem, try to <a href="https://support.mozilla.org/kb/troubleshoot-mode-thunderbird">reproduce the problem in Troubleshoot Mode</a>, then file a bug report for <a href="https://bugzilla.mozilla.org/enter_bug.cgi?product=Thunderbird">Thunderbird</a> or <a href="https://bugzilla.mozilla.org/enter_bug.cgi?product=Calendar">Calendar</a>.
Os byddwch yn dod o hyd i broblem, ceisiwch <a href="https://support.mozilla.org/kb/troubleshoot-mode-thunderbird">atgynhyrchu'r broblem yn y Modd Datrys Problemau</a>, yna ffeilio adroddiad gwall ar gyfer <a href="https://bugzilla.mozilla.org/enter_bug.cgi?product=Thunderbird">Thunderbird</a> neu'r <a href="https://bugzilla.mozilla.org/enter_bug.cgi?product=Calendar">Calendr</a>.