Libraries often want to use the third built-in overdue notice as a billing notice for lost items. The timing for overdue notices is set in Tools >
Overdue notice/status triggers. However, lining up the timing for this notice and
DefaultLongOverdueDays requires some consideration.
The timing set for your third overdue notice Delay will send a notice when items are that exact number of days overdue. So, if the Delay is set to 60, ODUE3 will send when items are 60 days overdue. However, remember that the longoverdue.pl cron marks items as long overdue when they are over the number of days set in DefaultLongOverdueDays (or directly in the longoverdue.pl cron). In practice, this means that if both the ODUE3 trigger and DefaultLongOverdueDays are set to 60, patrons will receive their ODUE3 the day before they are billed for the item by the longoverdue.pl cron. To reduce patron confusion, ByWater recommends phrasing your ODUE3 to indicate that items will be billed to their account (instead of has been billed).
Note also that once an item is marked long overdue, Koha cannot send an ODUE notice for it even if it still shows as checked out to the patron (that is, it is not considered 'returned' by MarkLostItemsAsReturned). Thus, if a library sets their Delay to a higher number than what is set in DefaultLongOverdueDays, patrons will not receive ODUE3 for those items.
The final consideration is your library's OverdueNoticeCalendar setting. If this is set to 'Use calendar', Koha will skip closed days as set in Tools > Calendar when counting toward your Delay. However, there is no option to skip closed days for the longoverdue.pl process, so items may end up being automatically marked lost before the billing notice has a chance to send. For this reason. ByWater recommends that libraries who use ODUE3 as their billing notice set this to '[Ignore calendar] when working out the period for
overdue notices.'