The error is passed onto imapsync from the Mail::IMAPClient module, what version are you using?
You should be able to find out using the following command:
Code:
perl -mMail::IMAPClient -e 'print $Mail::IMAPClient::VERSION, "\n"'
It might also be from the Date::Manip module, the version of that can be found using:
Code:
perl -mDate::Manip -e ''