Hello,
these are system messages and I think you can configure the "From" address for these messages in the System messages configuration options, for example, for the password reset:
When you edit the entry:
However as explained on the settings page, if it is left blank it should default back to noreply@domain (where domain is the domain of the e-mail address being reset, I guess).
I would first check what is your current value for this. If it is actually blank and gmail is complaining about a missing From header, I would say there might be a bug here.
You could set it manually to something you would like to be the From adresss for these messages to see if it fix the problem.
Kind regards
Sébastien Riccio
System & Network Admin
https://swisscenter.com