What email apps is BusyCal compatible with?

BusyCal can use your calendar service or a compatible mail app to send meeting invitations. The route depends on the calendar that contains the meeting.

BusyCal

Invitations sent by your calendar service

For calendars that support automatic scheduling, such as iCloud, Google Calendar, and Microsoft Exchange or Microsoft 365, the calendar service normally delivers invitations during sync. Your choice of email app does not control that delivery. See Meetings and Invitations.

Invitations sent through a mail app

Local calendars and other cases that require an emailed invitation use a mail app to prepare a message with an .ics attachment. BusyCal needs an integration that can pass the recipients, message, and attachment to that app.

Built-in integrations include Apple Mail, MailMate, Airmail, Outlook, Thunderbird, and Postbox, with these limits:

• Outlook requires a version that supports the AppleScript commands used to create messages and attachments. A version without those commands cannot use this integration.
• Thunderbird and Postbox prepare a message for you to send yourself. They do not support automatic sending through BusyCal.
• macOS may ask you to allow BusyCal to control the mail app. Allow that request if you want to use the integration.

MailMaven, Spark, and browser-based email such as Gmail in a browser do not currently have a built-in integration for this invitation handoff. Setting one as the default email reader does not add attachment automation. BusyCal may use Apple Mail or another supported running mail app instead.

An email app's general AppleScript support does not by itself establish compatibility; BusyCal also needs a matching integration.

BusyContacts

Writing an email to a contact and showing that contact's message history have different requirements. For default email apps, Spotlight, MailMate, Apple Mail's extension, and MailMaven compatibility, see What email apps is BusyContacts compatible with?.