Affects Version/s: 7.1.X, 7.2.X, Master
For system emails related to user accounts, a unique message ID is not generated, so for some email servers like MS Exchange, one email will be dropped.
This goes against the RFC 288 standard:
3.6.4. Identification fields
Though optional, every message SHOULD have a "Message-ID:" field.
The "Message-ID:" field contains a single unique message identifier.
For messages related to message boards, this is already done by using the timestamp from the modified date of the message. This ensures all message IDs send over email are unique.
Steps to reproduce:
1. Configure a clean bundle to use your gmail account :
2. Go to Control Panel > Configuration > Instance Settings > Email > Email Sender.
3. Change the Address field to the email used as a mail server. Save.
4. Go to Control Panel > Users > Users and Organizations
5. Add a new user.
6. Reset the user's password, checking the "Require Password Reset" option.
7. Log into the email server account setup in step 1.
8. Go to the "Sent" folder"
9. View the message IDs of the two messages sent to the newly created user (one for account creation, one for password reset).
Expected results: Message IDs are unique.
Actual Results: Message IDs are the same (unique per-user, not per-user's notifications).
Reproduced on master: ae69e39b628a47ee4a64eaff6ab69855a7e3a5cf