[Snortibartfast]

I used Alpine as my main email client for a while. I really like it, but I had problems with Fastmail's LDAP-addressbook. And if I remember correctly I couldn't use Office365's addressbook either.

Another problem was integrating Alpine with calendars (at least O365).

khal (with vdirsyncer) is a nice calendar app. I haven't got it working perfectly with Office635 yet though; I use a read-only url to the calendar, so I can at least see it, but cannot edit it. The Fastmail calendar works.

[kxyvr]

My solution has been to use the Fastmail website to accept calendar invites, but use khal and vdirsyncer to manager the majority of my calendar. As far as contacts, I believe Fastmail can import and export to vCard, which can be managed locally with khard and vdirsyncer as well. I use khard directly with mutt to access email contacts and I've been happy with it.