About
A Message-ID is an email identifier. It is generated by the client sending the mail and added in the Message-ID header
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Structure
An message id is generally the concatenation of:
- a timestamp
- the local hostname of the sender
Example
Examples of two differents message id header
Postfix
Generated by postfix
Message-ID: <[email protected]>
This id seems to follow the algorithm describe in Recommendations for generating Message IDs where:
- 20200612190818 is the current (wall-clock) time in the highest resolution to which you have access (most systems can give it to you in milliseconds, but seconds will do)
- 3E16E1FBE8 comes from:
- the random generation of 64 bits (for postfix, 60, 4 bits for one character)
- encoded to base 36 characters (0-9 and A-Z)
Javax Mail
Generated by Javax Mail
Message-ID: <[email protected]>
Message-ID: <hashcode>.<id>.<currentTime>@<hostname>
where:
- hashcode is the hash code of the new java object created to build the id
- id is a global ID (incremented on every use)
- currentTime is the current time (in milliseconds)
- hostname is the host name where the program is running
Management
See
With the Gmail original message
