SMTP uses several ports, but only two of them really matter for sending email today: 587 (with STARTTLS) and 465 (with implicit TLS). Use 587 if your client supports STARTTLS, otherwise use 465. Avoid port 25 unless you’re running a mail server.
Where each port comes from
| Port | Encryption | Status | Use it for |
|---|---|---|---|
| 25 | None or opportunistic STARTTLS | Server-to-server only | Mail-server — not for client submission |
| 587 | STARTTLS (TLS upgraded after handshake) | Recommended for client submission | Sending through Mailpro from apps, scripts, devices |
| 465 | Implicit TLS (encrypted from the start) | Widely supported, modern | Use when 587 / STARTTLS isn’t available |
| 2525 | Same as 587 | Fallback | Some hosts block 587 outbound |
Is port 587 always encrypted?
STARTTLS upgrades a plain connection to TLS, so technically the first handshake is unencrypted. In practice, every reputable provider (including Mailpro) requires the upgrade and refuses to deliver if it fails. Detail: is port 587 always encrypted. Background: port 465 vs 587.
Where to find the right values for Mailpro
Mailpro’s SMTP host, port, username and password are listed in your account settings. See where to find the SMTP server. Authentication details: SMTP authentication. To pick the right SMTP server type for your use case: SMTP server type.
Configure your sender once and forget it
Use port 587 with STARTTLS, the SMTP host shown in your Mailpro account, and SMTP authentication. Need step-by-step? See how to send emails with the SMTP server.