VPS port 25 blocked: how to get outbound SMTP unblocked
Many VPS providers block outbound port 25 by default to prevent spam. To run your own mail server you need it open: test the connection, ask your provider to unblock it (or choose one that allows it), and prepare reverse DNS, SPF, DKIM and DMARC before you send.
Check whether port 25 is blocked
From the VPS, try to open a connection to a public mail server on port 25 (for example with telnet or nc to a major provider's MX host). If the connection times out, outbound port 25 is probably blocked at your provider, not on your own firewall.
What to ask your provider
- State that you run your own mail server and will send only to recipients who have consented.
- Give the domain and IP address, and confirm reverse DNS (PTR) will match your mail hostname.
- Ask what daily or hourly sending limits apply. We set your TurboMTA sending policy to match them.
Before you send
- Set reverse DNS (PTR) so the IP resolves to your mail hostname, and make the A record match.
- Publish SPF, DKIM and DMARC records for your domain.
- Warm new IP addresses up gradually and stay within your provider's limits.
- Honour unsubscribe requests and keep complaint rates low.
Need help?
Free setup is included with TurboMTA. Open a ticket and we will configure it with you.
Frequently asked questions
Why is port 25 blocked and what can I do?
Many VPS providers block outbound port 25 by default to limit abuse. Ask your provider to unblock it, or choose a provider that allows it. We cannot unblock it for you, but we will tell you what to ask for and set a sending policy that fits the limits your provider gives you.
Does it handle SPF, DKIM and DMARC?
TurboMTA signs mail with DKIM and guides you through the SPF, DMARC and reverse-DNS (PTR) records that mailbox providers expect. DNS changes are made by you or, with the free setup, through a support ticket. Correct records improve deliverability but never guarantee it.