Hello,
From your project description, here is our understanding.
1. You are using interspire application
2. Operating System is Debian
3. Webserver:Nginx
4. Control Panel: Plesk
5. Mailserver: Qmail or Postfix
Here is your current setup.
1. You will be sending campaign mails from your interspire application. There will be lot of mails which will be sent out from the mail application.
2. Currently, (assuming) postfix is running and mails are reaching to spam or detected as bulk mails.
Expectation:
1. Setup SPF & DKIM on the server so that mails will be signed and google will not detect the mails as bulk mails
Our Approach:
1. Incase postfix running, I will setup opendkim and sign all the outgoing mails by opendkim.
What we need from your end.
1. Server access
2. Domain Name
3. Nameserver access incase if external namesever used.
We will be available between 9:00 AM IST to 9:00 PM IST. If requires, we will be available on off working hour as well.
Let us know incase if you have any queries.