RFC 3700:Internet Official Protocol Standards
RFC-Ref

POP


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... Security -------- The SYS and AUTH POP Response Codes 3206 -------- MIME media types ...


... TCP MD5 Signature 2385 Option POP-URL POP URL Scheme ...
... POP-URL POP URL Scheme 2384 -------- Interoperation of Controlled-Load Service ...
... Redundant Audio Data 2198 IMAPPOPAU IMAP/POP AUTHorize Extension for Simple 2195 Challenge/Response ...



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