Earlier quoted context omitted.
The company I work for is big-ish, ~10k, and many use mutt, emacs, Thunderbird and some even use a mailing-list nntp with slrn. I think it all depends on which area of work you are in. For software engineering folks it works just fine. I for one use mutt and handle calendar invites with gcalcli, I can use LDAP lookup and HTML mails are converted using elinks and read inside mutt. If I want to see all the fanciness I…
I have hard time believing that more that 1% of a 10k employees company use Mutt.
I still use Mutt to quickly prune emails in the AM and for writing to mailing lists.
I've (sadly) gotten pretty used to Outlook and like it quite a bit. I do miss using vim to edit emails though...