0.5.1α is a bug fix release:

* fixes crash on invalid IM addresses
* fixes crash on invalid events without start time

What's new in 0.5α:

* support for vCard 3 for CardDAV compliance (should fix problems with DAViCal etc.)
* support for custom email/phone/address types
* support for IM addresses
* support for organization/job title
* many small improvements
* many bug fixes

What's new in 0.4.4α:

* CalDAV: ignore collections without VEVENT support (for instance, VTODO collections)
* provide DTEND for single-time events and DURATION for recurring events to Android calendar data provider (fixes #60)
* allow to enter account name at the end of account setup (fixes #13)
* advise user to enter email address as account name (closes #24)
* support for iCal TRANSP (availability free/busy field)
* create better UIDs using iCal4j UidGenerator and Settings.Secure.ANDROID_ID
* better ORGANIZER/ATTENDEE support, but there are big Android issues yet
* various improvements and bug fixes

What's new in 0.4.3α:

* security fix: validate certificates and not only host names (thanks Günter)
* support for iCal reminders
* better support for recurring events
* better support for timezones
* many other bug fixes and enhancements

What's new in 0.4.2α:

* workaround for KitKat settings activity crash bug (see issue #92)
* allow IP addresses at SSL hostname verification (see issue #88)
* imports "calender default time zone" at account creation
* bug fixes

What's new in 0.4.1:

* deal with encoded/invalid URLs one more time
* don't manually decode URLs for comparing (because we now always use encoded URLs)
* .ics: VERSION before PRODID
* refactoring: move WebDavResource.httpClient to new singleton DavHttpClient
* close input streams in propfind/multi-get

What's new in 0.4-alpha:

* SNI support (only available for API level >= 17 [Android 4.2+])
* fixes multiget request bug that caused unexpected results (empty files) from servers
* better handling of invalid URLs (with unencoded "@" and " ", for instance)
* better importing of calendar colors at account creation

Version 0.3.8-alpha

* calendar colors are imported when server specifies <calendar-color xmlns="http://apple.com/ns/ical/"> property
* introduced RoboHydra tests for future stability
* always try to repair URLs (should work around most problems with invalid ":", "@" etc. in URLs)
* always append trailing slashes to collections (fixes some redirection problems)
* refactoring, bug fixes

What's new in 0.3.7-alpha:

* support for structured addresses
* improved photo parsing/writing

* iCal4j/iCal4j-vcard update
* many (crash) bug fixes

Version v0.3.6-alpha

* introduced main activity with launcher icon, help, action buttons, verversion number
* don't follow redirects (see issue #52)
* better vcard parsing error logging
* always append trailing slash to collection URLs
* decrease MAX_UPDATES_BEFORE_COMMIT to 25 (may fix issue #25)