In a previous post regarding mutt I recommended notmuch for searching mail and goobook for accessing contacts. For some time now I've replaced both of these tools with a different tool called mu that accomplishes both tasks quite efficiently.
mu provides indexing for Maildir and has several command-line options for searching mail, extracting attachments, exporting contact lists and much more. Consequently it works quite well with offlineimap and mutt. There's very little change needed to implement it and in my experience it is much better at searching mail than notmuch and much quicker at getting contact info than goobook.
[Account Gmail] ... postsynchook = mu index --maildir ~/.mail
bind editor <Tab> complete-query set query_command = "mu cfind --format=mutt-ab '%s'" macro index Z "<shell-escape>mu find --clearlinks --format=links --linksdir=~/.mu/results " "mu find" macro index S "<change-folder-readonly>~/.mu/results<enter>" "mu find results"
Just download mu and follow its simple instructions to index your maildir then add these changes to your config files. Now offlineimap will run mu's indexer at the end of each sync and when you start a new email in mutt you can hit tab to complete recipients. If you want to search mail you can use my Z binding and utilized mu's many search features. That's it!