[TECH SUPPORT] LPS-49600 Message-ID is not unique

https://issues.liferay.com/browse/LPS-49600
http://tools.ietf.org/html/rfc5322#section-3.6.4 or http://tools.ietf.org/pdf/rfc5322

Hi Sergio,

I'm forwarding you two pulls to let you see Ákos' original approach as well. Here is the other one: https://github.com/sergiogonzalez/liferay-portal/pull/1627

Let us know if you have any questions.

Regards,
Tibor

/cc @akosthurzo