Interspire Email Marketer: Configure local SMTP (Postfix) on Contabo VPS to send newsletters

I have a working installation of Interspire Email Marketer on my Contabo VPS (Ubuntu 22.04 with Plesk). The system is ready but it cannot send any emails. I need an experienced freelancer to configure the local SMTP server (Postfix) so that Interspire can send newsletters directly from my own server – without using any external SMTP provider (no Amazon SES, no SendGrid, no third-party services).

What needs to be done:

· Review current Postfix configuration on the VPS.
· Configure Postfix to allow relaying from localhost (127.0.0.1) for Interspire.
· Adjust Interspire email settings to use local SMTP (localhost:25 or localhost:587 with proper authentication if needed).
· Ensure SPF, DKIM, and DMARC records for the domain news.sendora.gr are correctly set up (DNS is managed in Plesk).
· Set up or verify cron jobs for Interspire to process scheduled sending, bounces, etc.
· Test sending a real newsletter to a few email addresses (e.g., Gmail, Yahoo) and confirm delivery to the inbox (not spam).
· Provide brief documentation of the changes made.

Environment:

· VPS: Contabo
· OS: Ubuntu 22.04
· Control panel: Plesk (latest)
· Email marketer: Interspire Email Marketer (already installed)
· Domain: news.sendora.gr

The final result must be:
Interspire can send up to 160,000 emails per month using the local SMTP server, with good deliverability (properly configured SPF/DKIM/DMARC).

Please apply if you have:

· Proven experience with Interspire Email Marketer.
· Strong knowledge of Postfix configuration on Plesk/Ubuntu.
· Ability to work via remote access (SSH, Plesk login) and respect confidentiality.
· Examples of similar work or testimonials.

Budget: open to your offer, but I expect a fast turnaround (1-2 days maximum).

I will provide: full access to Plesk and SSH.