vCalendar RRULES: finding good docs on the Monthly recurring patterns.


Don B

I'm hoping we are doing some wrong that is obvious to the Outlook experts on
this list.

Executive summary: I'm looking for documentation for the RRULE of an
iCalendar that is specific to Outlooks implementation. I have the RFC-224
documentation and most things work, but Outlook doesn't appear to support
the standards as I read the specs. I'm looking for either documentation or
someone I can hire for a couple hours to show us how this works in the real

We are using the iCalendar format from an Intranet application to create
Outlook meeting requests. We have all the single day events working and some
recurring events are working. All the daily and weekly recurring
combinations work fine.

But Monthly recurring is giving us issues if we try to do specific days of
the week or last days of the month type patterns. For example, the following
rule works and opens correctly into Outlook:


(First day of the month for 3 months)

If we change the BYMONTHDAY to -1, expecting to get the last day of the
month, Outlook throws a "Cannot import vCalendar file." error.

If we change to BYDAY=1SU (expecting the 1st Sunday of the month) it also

We need to support ALL the possible combinations you can view in the
interface but we can't get the 1st Monday of the month or the last Monday of
the month to work (or other days...).

I'm willing to pay someone for results if they know the secrets to getting
these working. Note that I may be looking to outsource some additional
Outlook integration work in the future. We have an application that needs to
do some Exchange free/busy and GAL lookups/displays via an Intranet
application. But this issue is time critical for me so any
references/assistance is appreciated.

Don Baarns
Baarns Consulting Group, Inc.
Co-author: Excel 97 SDK (Microsoft Press)
Aug 3, 2012
Reaction score
I am strugling with the same things.
Apparently there is some kind of consistency check.
If You change BYMONTHDAY=-3 than you have to adjust the DTSTART and DTEND to be consistent so DTSTART has to be on that same day (3 from last).
And Dtend shoul be cosistent also
Try that And it might work
Good luck

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