Mutt: color messages with attachments differently

You need to run the tag-pattern command. The default for that is T (Shift+t). You can then give it a regular expression. By default this will match message subjects.

If you need to select a range of messages by number, you can provide the ~m [MIN]-[MAX] pattern to tag-pattern. There are many other options I've found useful over the years, and you can see a complete list in the “Advanced Usage - Patterns” section of the manual.

You can also use t to tag or untag the highlighted message, to fine-tune the selection.

Then you can run tag-prefix (;) followed by save-message (s), and it will prompt you for a mailbox name. This command marks the saved messages to be deleted; there is also the copy-message command (C, i.e. Shift+c) to copy without marking for deletion.

The link that SEoF provided was a great suggestion. The blog post is incomplete, in my opinion, but it did get me started on the right track. I did some more digging and came up with a complete list of steps for getting Office 365 to send me meeting invites in iCalendar (.ics) format.

Note that I'm not an administrator and I didn't need to contact anyone to give me any privileges. The only caveat is that you need access to a Windows box. Once you change the settings via Windows, you can go back to using whatever OS you were using before. I did the following on my own as a normal user using Windows 7:

1. Download and install Microsoft .NET Framework 4.5 from http://www.microsoft.com/en-us/download/details.aspx?id=30653.
2. Download and install Windows Management Framework 4.0 (Windows6.1-KB2819745-x64-MultiPkg.msu) from http://www.microsoft.com/en-us/download/details.aspx?id=40855.
3. Run PowerShell as an administrator.
4. Set-ExecutionPolicy -ExecutionPolicy RemoteSigned
5. $UserCredential = Get-Credential
   • Enter your email address and password.
6. $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
7. $ImportResults = Import-PSSession $Session
8. Get-CASMailbox -identity YOUR@EMAIL.ADDRESS | Format-List
9. Set-CASMailbox -identity YOUR@EMAIL.ADDRESS -PopUseProtocolDefaults:$FALSE -ImapUseProtocolDefaults:$FALSE -PopForceICalForCalendarRetrievalOption:$TRUE -ImapForceICalForCalendarRetrievalOption:$TRUE
10. Remove-PSSession $Session
11. Set-ExecutionPolicy -ExecutionPolicy Restricted

Now, my mutt on Linux is retrieving meeting invitations in iCalendar (.ics) format.