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IMAP4REV2
IMAP4REV1
CalDAV
CardDAV
Exchange Active Sync
Microsoft Commitment to Interoperability
Core: MS-ASHTTP - MS-ASCMD - MS-ASWBXML - MS-OXPROTO - MS-ASDTYPES
Features: MS-ASEMAIL - MS-ASCNTC - MS-ASCAL
Additional: autodiscover.xml
IMAP4EXT+
Some extensions that are not part of IMAP4REV1 or IMAP4REV2
JMAP
Sieve
Officiel / Reference Website
Base RFC: RFC5228
Extensions: ToDo
Correctness
Behavior tests, Unit tests, RFC compliance tests, Distributed Invariant tests, Fuzzing, etc.
Performances
Microbenchmark, production reporting data through OpenTelemetry, etc.
Interop
SASL for example