Mail w/ multiple domains - mail server host name

A bit new to managing my own email server. I have the mail stack installed and working for multiple domains on my AWS server but I did not change anything in the organization setup mentioned here for lack of experience in knowing what specifically to change, especially with 3 different domains using the mail server:

var/www/22222/htdocs/vimbadmin/application/configs/application.ini +250

I did however change my hostname and confirmed after reboot typing hostname returns mail.mydomain.com (the most “important” domain) however in email headers I am seeing the long AWS host name with the internal ip (ip-172-73-73-23-us.west.internal…) vs mail.mydomain.com.

How do I go about fixing this? Even better, is it possible for me to set each mail account to use mail.domain-for-this-email-user.com for sent emails?

Thanks.

Maybe this post will help: GoDaddy not receiving emails

Hi @THORR thanks and ironically I had that thread open on another tab and was going through the list @rahul286 referenced. I’ll post back if I end up making further headway on this. My first goal is to rid myself of the constant SSL exclusion requests thunderbird keeps me for.

Oh and the Reverse PTR was something I had to request Amazon to adjust in their DNS, took a few days but once they did that, and even though I only could provide a single domain, all emails began working without being blocked…aol being the biggest pain.