You're going to struggle with email if you don't have a good grasp of DNS. If DNS isn't right you will be blocked by pretty much everything. If you manage to create an open relay your domain will be blacklisted pretty quick too, so be careful. That tool will give you what you need.
SMTP Banner CheckReverse DNS does not match SMTP Banner
Deliverability is a challenge. I wanted to make sure you had the tools. PTR is the first thing to check.
You're going to struggle with email if you don't have a good grasp of DNS. If DNS isn't right you will be blocked by pretty much everything. If you manage to create an open relay your domain will be blacklisted pretty quick too, so be careful. That tool will give you what you need.
Pointer record IP > name for the banner you can create a cname that matches the banner and add that to the ptr.