dbox: message internal date

[Francesco]

Hello everyone and thanks in advance for the help :)

I'm trying to figure out where does dovecot store the message internal
date when using single dbox storage format.

In Maildir format, the internal date is determined by the actual date of
the file on the filesystem, but in dbox it doesn't seem to be the case.

I'm looking forward for a way to modify a message internal date when on
a dovecot instance running dbox storage engine, maybe anyone knows if
it's possible and how to accomplish this?

Again, thank you for the help
Sincerely
Francesco