Everything is LGPLv2.1 (see COPYING.LGPL) unless otherwise mentioned at the

beginning of the file. Almost everything in src/lib/ is with MIT license.

The exceptions are:

src/lib/

- md5.c : Public Domain

- base64.c, utc-mktime.c : BSD-like (read it)

- primes.c, printf-upper-bound.c : LGPL v2

src/lib-storage/mail-thread.c : merge sorting code is with MIT license.