Message-ID

Die Message-ID ermöglicht die eindeutige Identifizierung einer Nachricht und ist daher in jeder enthalten.

M2 generiert sie wie folgt:

• It will always start with "<op".
• The next 6 characters are a semi-base36 (defined below) representation of the time_t returned from ::time() (seconds since 19700101 000000UTC)(bonus-points to the first person giving the exact time this will roll-over  :-)
• The next two characters are semi-base36 of either the 10 least significant bits of the milliseconds time of day (for Win32), or a 10-bit random value (all other platforms).
• The next 6 characters are semi-base36 of either the most significant 4 bytes of a 16-byte MD5 checksum of the From:-address, or a random 32-bit value (if for some reason From: is missing).
• Personalization
• "@"
• IDNA-version of the FQDN

In short:

<op[seconds since 1970][millisecond|random][md5 of From: random][personalization]@[idna-fqdn]>