Email & port 25

Outbound connections on port 25 (server-to-server email) are blocked by default on every new account.

Why

Spam from a single server can get a whole range of IP addresses blocklisted, which hurts every customer. Blocking port 25 by default is the most effective way to stop that.

What still works

Receiving email on port 25 (inbound is not blocked).
Sending through an email provider on ports 587 (submission) or 465 (SMTPS) — this is the recommended way to send from apps.
All other ports.

Example: send via a provider on port 587

SMTP_HOST=smtp.your-provider.com
SMTP_PORT=587
SMTP_USER=apikey
SMTP_PASS=...

Requesting port 25

If you need to run your own mail server, open Email sending in the console and tell us what you'll send and how you handle bounces and unsubscribes. You can request it once your account has been in good standing for 30 days (verified, paid, and no abuse reports). We reply by email, usually within one business day.

Before you ask

Set reverse DNS on your server's IP to your mail hostname, and publish SPF, DKIM and DMARC records for your domain. We check these.

Port 25 can be closed again if we receive spam complaints. See the Acceptable use policy.

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