Revert "LPS-29279 Make sure mailId is unique for every single mail"

This reverts commit 127761da35f83d453da7beab6080a0ee46b97be4.
LPS-49600 Add ability to append a generated unique mailId
LPS-49600 Use new constructor when necessary
LPS-49600 Fix MB which uses In-Reply-To header
Revert "LPS-49600 Use new constructor when necessary"

This reverts commit d1dc97352fc08657877571d50850622f839c5d4c.
LPS-49600 Simplify