Fix VPS Sendmail Failure

Job ID: 40445669

Budget: $30 – $250 USD

Emails generated from my VPS are never leaving the box. Both the live booking system and the two PHP test pages below should trigger a simple confirmation message, yet nothing reaches any inbox:

• https://castawaysres.com/castaways_portal/test_mail.php
• https://thresholdtestingsite.com/castaways/reservations/test_mail.php

I’m relying on the server’s built-in Sendmail, but even a direct Sendmail call returns nothing. I have not inspected the mail logs yet, so the root cause—mis-configuration, queue backlog, DNS (SPF/DKIM), blocked ports, or something else—still needs to be identified.

Here’s what I need from you:
1. Connect to the VPS, inspect the relevant log files (/var/log/maillog or equivalent) and pinpoint why messages never leave the server.
2. Apply whatever configuration fixes are required—Sendmail relay, hostname tweaks, DNS records, queue flush, or an alternative lightweight SMTP relay if Sendmail proves unworkable.
3. Confirm success by running both test_mail.php pages and showing the messages arrive in a real mailbox.
4. Leave me a brief note outlining what you changed so I can keep things working long-term.

Root access is available as soon as you’re ready. I’d like to see those reservation emails flowing again today if possible.
Related categories: PHP Linux Apache DNS VPS Postfix SMTP System Administration