Connect any SMTP service

Grade school

Use this only if your email service isn’t on our list. It works, but the listed ones are safer and easier.

High school

Use Other SMTP only when your provider has no dedicated mailer in the list. WP Mail SMTP describes it as less secure and less reliable than API mailers, because it signs in with a username and password and gives fewer error details.

College

SMTP submission authenticates with a long-lived username and password stored in WordPress, and failures surface as SMTP reply codes rather than structured API errors. It’s still a valid, standard route when an API mailer isn’t available.

Postgraduate

Prefer transports that support scoped, revocable credentials and structured delivery events. Where SMTP is unavoidable, use a provider-issued SMTP credential dedicated to this site rather than a person’s mailbox password.

Developer

SMTP submission (RFC 6409): typically port 587 with STARTTLS, or 465 with implicit TLS. Hosts may block outbound 25. Use the provider’s documented host name, never a hard-coded IP.

Grade school

Your email service tells you a server name, a number (port), and a username and password. Copy them exactly.

High school

Get these from your provider’s own documentation or dashboard — they’re different for every provider:

• SMTP host — for example smtp.provider.example
• Encryption and port — usually TLS on 587, or SSL on 465
• Username and password — an SMTP credential from the provider

You’ll still need to authenticate your domain with that provider’s own DNS records.

College

Provider values vary: some use a fixed literal username (SendGrid’s is apikey, with the API key as password), others issue separate SMTP keys. Don’t reuse another provider’s host or port. If you use Google Workspace or Microsoft 365, use their dedicated OAuth mailers (the Microsoft 365 mailer needs WP Mail SMTP Pro) instead of putting a mailbox password into SMTP settings.

Postgraduate

A mailbox password in SMTP settings couples your storefront to a person’s account and bypasses modern sign-in controls. Dedicated relay credentials keep sending independent of staff changes and can be rotated without affecting anyone’s mailbox.

Developer

Placeholders only: host=smtp.provider.example, port=587, encryption=tls, auth=true, credentials from your environment. Enable Auto TLS. Store with WP Mail SMTP constants where possible.

Grade school

In your website’s settings, pick “Other SMTP”, type in the details, and send yourself a test.

High school

1. Open WP Mail SMTP → Settings, set your branded From Email and From Name, and tick both Force options.
2. Choose Other SMTP, enter the host, encryption and port.
3. Turn on Authentication and enter the username and password yourself.
4. Save, then send Tools → Email Test to your own branded address.

College

Check that the From address is one your provider allows for that credential; many relays reject or rewrite unauthorized senders. Verify SPF, DKIM and DMARC on the received message, not just that it arrived.

Postgraduate

Treat the SMTP credential like any other secret: dedicated to this site, rotated on staff or vendor changes, and stored outside the admin database where possible.

Developer

If WP_HTTP_BLOCK_EXTERNAL is set it doesn’t govern SMTP sockets; outbound port rules at the host do. Test connectivity with the plugin’s debug output rather than repeated sends.