Mutt and Office365

For reasons, I now need to interact with Office365 mail and calendar. It should go without saying that the Outlook webapp is almost painfully unusable (there really is no key binding for “next unread email”). Thus began the quest to get mutt interacting with the O365 server. This was a rather painful process: so much of the information on the web refers to earlier authentication schemes, Microsoft-special protocols, things that don’t support 2FA, dead Linux software, useless Linux software, etc.

After many false starts, I eventually found a working solution that allows mutt usage (and my treasured key binding for “mark current thread as read and move to the next unread email”). That solution is davmail. Yes, it’s on sourceforge, and yes, it’s Java, but it works perfectly.

It’s not very well-documented, but you can run it in headless mode and still do the interactive OAuth2 flow needed with modern O365. Your settings should include:


When davmail starts, it will ask you to visit a URL and paste the resulting URL back - this contains the necessary OAuth2 tokens it needs. No need for any GUI!

Once davmail is running, your .fetchmailrc can be:

poll localhost protocol IMAP port 1143
 auth password username "[email protected]"
 is localuser here
 sslmode none
 mda "/usr/bin/procmail -d %T"
 folders INBOX,etc,etc

Note that since davmail is running locally, there’s not really any need for SSL, though you can set that up if you like.

When you start fetchmail, enter your password, and that will initiate the auth flow against the davmail instance. Note that you’re not storing passwords anywhere, unlike the old-style app password approach you might have used previously on gmail and the like.

I don’t need to send mail often, so I have mutt set up like this:

set smtp_url= "smtp://[email protected]@localhost:1025/"
unset smtp_pass
set ssl_starttls=no
set ssl_force_tls=no

Having to enter my password each time is not a big deal for me.

Equally I have my calendar app set up to pull over caldav from davmail. Works great. I’d love to be able to pull my O365 calendar into Google Calendar, but apparently Google and Microsoft are unable - or more likely unwilling - to make this work in any meaningful way.

I’m pretty sure it’s possible to adapt Google’s OAuth2 scripts to directly use fetchmail with O365’s modern auth stuff, but I’m not sure I have the energy to figure it out - and as far as I can find, nobody else has?