We have a number of unit tests that probably work just as well for POP3 as they do for IMAP. For example: - test_imap_mime probably wants to be reused to the maximum extent possible for POP3. - Sync tests not related to specific edge-cases of our IMAP implementation would want to be used too. Some of these may be best factored out into more general sync tests. - mutation operations can get coverage too, it's just that for most of them we only expect local operations to fire. only deletion should trigger a server operation. I think this can all be dealt with in the back-end. This wants to be implemented for our full-message sync on bug 916083 and probably wants to put us in a full-message-sync mode. The partial sync behaviour will be specific to POP3.

Landed support in bug 832924. Commit hashes, for reference: https://github.com/mozilla-b2g/gaia/commit/093922c5ffc0e051d0d30067238208222725a09d https://github.com/mozilla-b2g/gaia-email-libs-and-more/commit/da544eb9c5e7a28c8cccb4d49cc57d8ee548b05a