Outlook's calendar supports multiple time scales, from 5 minutes to 1 hour. While you can't make your own interval, you can change the scale to one more suitable for your needs.
Move meetings without losing the ability to "Send Update"
When you migrate meetings from an Outlook mailbox or PST file to another Mailbox or PST file, you will be missing the "Send Update" option.
Add Holidays to Outlook's Calendar
Create a Custom Holiday File (HOL) to share any type of all day event with other Outlook users. We include a sample file that counts the days since Jan1 and the number of days left in the year.
Searching Outlook's Calendar
Instant Search can handle most searches, Advanced find can search more fields and Query Builder lets you refine your searches, but you can't save the searches or print the results.
Meeting Times not correct in Outlook 2010
A user complained about the GMT offset not being applied to meetings received from other time zones in Outlook 2010: "Having an issue with Outlook 2010 where the GMT offset is not being applied to meetings received from time zones other than local. Meetings appear ok on mobile email and webmail calendar as well as
How to Hyperlink to Appointments (icals)
A frequently asked question is "How do I provide a link for someone to click to add an appointment to their calendar?" The answer: save the appointment as an *ics file and upload it to a web server then link to it like you would any other file on the internet. You can use the same method
Changing the End Date on Recurring Appointments
How to end a recurring appointment or cancel future events in a recurring meeting and keep any exceptions (including notes in individual occurrences or appointments/meetings moved to different dates).
Force users to respond to meeting requests?
We're often asked if there is a way to force people to send an accept message, when the appointment goes into their calendar.
Response to this meeting request will not be tallied
When you create a meeting request in a secondary calendar, you'll get a message that responses to the meeting request won't tally because the meeting is not in your default calendar: This meeting is not in the Calendar folder for this account. Responses to this meeting will not be tallied. Do you want to send anyway?
Schedule meetings only during working hours
I'm getting meeting requests outside of my working hours. Is it possible to set Outlook to automatically decline meeting requests that are outside of these hours? Or at least notify the person sending the meeting request? You can't control it within Outlook. If it's a problem, create appointments for non-working time and mark them busy