I was testing mass mail ,and setup as following:

SMTP server : local postfix

Sender email address in template:  mymail@mydomain

receiver email address : mycolleague@mydomain

I found the mass mail can not be received by my colleague, even not in spam folder.

I guess it is caused by original sender in mail head is set as bounce+xx@mydomain, which is not same with "mail from"  email .

And if i set mydomain email server as SMTP , it will reject mail sending.

After calling to my email service provider, they confirmed it is because mismatch of sender and original sender.

And they  told me i can switch off the function of fake name detecting in admin panel.

But i just wondering whether my mass mail will be set spam flag in other receiver's server?

Or it is possible the let odoo do not set original email like bounce+xx@mydomain.

This setting seems used for collect and count the bounced mail, actually i dont care too much about how many mass mail will be bounced, but i do care my mass mail is flagged spam or not.