Legend
✔
The feature is available. Important restrictions are listed below the icon.
⚠
The feature is available, but data may be misrepresented in some rare cases. Details are given below the icon.
✘
The feature is not available.

Calendar Features

Mozilla Thunderbird¹ Microsoft Outlook Android²
Title
✔
✔
✔
Start and end
✔
✔
✔
Time zones
✔
✔
"Local time" is missing, but corresponding events are displayed correctly. Time zones are less fine-grained than in other applications.
✔
"Local time" is missing, but corresponding events are displayed correctly.
Recurrence rules and exceptions
✔
⚠
Events repeating on the second-last, third-last or fourth-last weekday of a month are not supported. If a recurrence rule falls on a nonexistent date (i.e. "30. every month" in February), the event may be displayed too often.
✔
Location
✔
✔
✔
Description
✔
✔
✔
Reminders
✔
⚠
Reminders after the event's start are not supported. At most one reminder per event.
✔
Attendees
✔
✔
✔
Invitations
✔
✔
Outlook only supports the message store's primary calendar when handling incoming invitations and replies.
✘
Scheduling status
✔
✔
✔
Availability
✔
✔
✔
Priority
✔
✔
✘
Confidentiality
✔
✔
✔
Categories
✔
✔
✘
Attachments
✔
Thunderbird can only attach websites (URLs).
✘
Attachments are not supported, as Outlook does not support attachments outside of the description field.
✘
Features only available within the same application n/a localization preferences for Microsoft applications ("Locale ID"). n/a
Restrictions when using GeneralSync calendars For compatibility reasons, monthly recurrence rules with multiple instances per month and complex imported recurrence rules may get simplified when saving. For compatibility reasons, text formatting and embedded content (images, attachments) within the event description is removed when saving.
For compatibility reasons, recurrence rules for arbitrary week- or weekend-days may get simplified when saving.
Additional internal Outlook fields might not get preserved.
For compatibility reasons, complex recurrence rules may get simplified when importing.

Address Book Features

Mozilla Thunderbird Microsoft Outlook Android²
Name and Nickname
✔
✔
✔
Photo
✔
✔
✔
Chat names
✔
One of each: AIM, Yahoo, Skype, ICQ, XMPP, IRC.
⚠
At most one name for each contact. As it is not possible to specify a type, the name will only be visible from Outlook.
✔
Skype, ICQ, XMPP. Additionally at most one SIP-Address per contact.
Email addresses
✔
At most two addresses per contact.
✔
At most three addresses per contact.
✔
Phone numbers
✔
One of each: work, home, fax, pager, mobile.
✔
Two of each: work, home. One of each: mobile, fax, fax (work), fax (home), pager, TTY/TDD, other. As custom fields, one each: Callback, Primary, Radio, Car, Assistant, Company, Telex, ISDN.
✔
work, home, mobile, mobile (work), pager, pager (work), fax, fax (work), fax (home), TTY/TDD, custom, other.
Homepage
✔
One of each: work, home.
✔
One of each: work, home, ftp.
✔
work, home, custom, other.
Postal addresses
✔
One of each: work, home.
✔
One of each: work, home, other.
✔
work, home, custom, other.
Birthday
✔
⚠
Incomplete dates (date without year or only the year) are not supported.
✔
Anniversaries
✘
⚠
Incomplete dates (date without year or only the year) are not supported. At most one anniversary per contact.
✔
Organizations / Companies
✔
One of each: company name, title, department
✔
One of each: company name, company name (phonetic), title, department, office location, role, identification number
✔
One of each: company name, company name (phonetic), title, department, office location, role
Languages
✘
✔
At most one language per contact.
✘
Relationships
✘
✔
One of each: spouse, referrer, assistant, manager. Any number of times: child.
✔
assistant, child, sweetheart, friend, manager, parent, partner, referrer, kin, spouse, custom.
Gender
✘
✔
✘
Hobbies
✘
✔
✘
Custom fields
✔
4 fields per contact
✔
4 fields per contact
✘
Notes
✔
✔
✔
Confidentiality
✘
✔
✘
Categories
⚠
Categories map to "address lists", which do not support contacts without email addresses nor multiple contacts with the same email address.
✔
✔
URL for availability information
✘
✔
✘
x509 certificates
✘
✔
✘
Features only available within the same application preferred message format, Visibility of the contact in email views. chat name (see above), importance, location, name display format, business card design, billing information, customer number, social security number, localization preferences for Microsoft applications ("Locale ID"). favorite contacts.
Restrictions within GeneralSync address books n/a For compatibility reasons, text formatting and embedded content (images, attachments) within the contact's note field is removed when saving.
"Follow up" is not fully supported.
Additional internal Outlook fields might not get preserved.
n/a

These tables refer to the latest version of GeneralSync and its add-ons / add-ins for each individual application.

¹ Calendar features in Mozilla Thunderbird are provided by the add-on "Lightning", which is installed by default.

² GeneralSync provides the listed features to other apps and the operating system. The set of available features also depends on your device and the app you use to access your calendar or contacts.