How Windows Mobile 6.5 Handled vCalendar Invites

Windows Mobile 6.5 handled vCalendar (.vcs) email attachments through its integrated Pocket Outlook suite, processing invites differently depending on whether the message was delivered via Microsoft Exchange ActiveSync or standard POP3/IMAP protocols. While Exchange connections offered automated, interactive meeting processing, standard email attachments required manual user intervention to parse and save event data directly into the device's local Calendar database.

Exchange ActiveSync vs. Standard Email

When connected to a Microsoft Exchange Server via ActiveSync, Windows Mobile 6.5 did not treat meeting requests as generic file attachments. The server converted meeting requests into specialized meeting objects before delivery. Upon opening the message, users were presented with native "Accept," "Tentative," and "Decline" soft keys at the bottom of the screen. Responding immediately updated the local Pocket Calendar and dispatched an RSVP message back to the organizer over the air.

For accounts using standard POP3 or IMAP4, the operating system treated the incoming invite as a raw .vcs (vCalendar) or .ics (iCalendar) MIME attachment (text/x-vcalendar or text/calendar). The email client did not render native RSVP buttons inside the message body for these standard accounts.

Processing the .vcs Attachment

When an email contained a .vcs attachment, Windows Mobile 6.5 processed the file through the following steps:

  1. Attachment Detection: The Messaging application identified the .vcs file in the attachment area at the bottom of the email header.
  2. File Association: Windows Mobile mapped the .vcs extension to the internal calendar executable (calendar.exe) via the system registry (HKEY_CLASSES_ROOT\.vcs).
  3. Importing the Event: Tapping the attachment launched Pocket Calendar in an import mode. The application parsed the standard vCalendar fields—such as SUMMARY, START, END, LOCATION, and DESCRIPTION.
  4. Saving to Calendar: A new appointment form opened, pre-populated with the extracted details. The user had to tap the "OK" soft key to confirm and commit the event to the local Object Store (PIM database).

Limitations and RSVP Handling

Outside of an Exchange ActiveSync environment, Windows Mobile 6.5 provided only one-way processing for vCalendar attachments. The operating system could read and store the appointment details locally, but it lacked the native capability to generate and send an automated response email (an iTIP/iCAL reply) back to the sender. To confirm attendance with the organizer, users had to manually reply to the email with a typed response.