Remove Message ID from SKIP_HEADERS constant

In the LegacyMailerHelper, the constant SKIP_HEADERS assigns the Message ID as a header to skip when creating an email. In one instance of ours, we already have a Message ID and want to use it to avoid sending duplicate emails. To make this work, we want to remove Message ID from the SKIP_HEADERS constant.

When we remove it, none of our emails are sending duplicates, which is great.
Also, when removed, other emails without an existing Message ID get a new one from Symfony Mailer.

Can you think of a reason it is not safe to remove the Message ID from the SKIP_HEADERS constant?

Sharing a patch we are using for consideration.

peace,
Mike