WP Mail SMTP setup with SecureSMTP: the Other SMTP settings, step by step

WP Mail SMTP is one of the most used WordPress plugins for sending email. It replaces WordPress’s default mail function with a proper SMTP connection. Its Other SMTP mailer works with any SMTP server, so you can point it at SecureSMTP and get authenticated sending, an email log for every message, and automatic bounce handling, while keeping the plugin you already know.

Every email WordPress sends then goes through SecureSMTP: contact form notifications from Contact Form 7, WPForms, Gravity Forms or Elementor, WooCommerce order emails, password resets and new-user emails.

Before you start

• A SecureSMTP account with your website added as a site. The free plan includes 5,000 emails a month.
• Admin access to your WordPress site.
• The WP Mail SMTP plugin (the free version is enough).

1. Copy your SMTP password

In the SecureSMTP dashboard, open API keys. The SMTP settings box shows the host, ports and username. The password is the site’s API key, which starts with qcs_live_. Copy it; you paste it into WP Mail SMTP in step 3.

2. Install WP Mail SMTP

1. In WordPress, go to Plugins → Add New.
2. Search for WP Mail SMTP, then click Install Now and Activate.
3. WP Mail SMTP may open its setup wizard. You can choose Other SMTP there and enter the settings below, or close the wizard and use the settings page.

If the SecureSMTP plugin is also installed, deactivate it. Two plugins that both take over WordPress email get in each other’s way.

3. Enter the Other SMTP settings

Go to WP Mail SMTP → Settings → General, scroll to Mailer and choose Other SMTP. Fill in:

TLS on port 587 is the usual choice. If your host blocks port 587, use SSL on port 465 instead. Always keep the encryption and the port together: TLS with 587, or SSL with 465.

Click Save Settings.

4. From Email and From Name

At the top of the same settings page:

• From Email: an address you read, on your own domain, such as [email protected].
• From Name: your site or business name. This is the name recipients see.
• Turn on Force From Email and Force From Name so every plugin uses the same sender.

What recipients see depends on whether your domain is verified in SecureSMTP:

To send from your own address, add your domain in SecureSMTP and publish the DKIM record it gives you. See Domains and DNS.

5. Keep the key out of the database (optional)

WP Mail SMTP can read its settings from wp-config.php instead of the database, so the key is not stored in your WordPress database or shown on the settings page. Add these lines above /* That's all, stop editing! */:

define( 'WPMS_ON', true );
define( 'WPMS_MAILER', 'smtp' );
define( 'WPMS_SMTP_HOST', 'smtp.securessmtp.com' );
define( 'WPMS_SMTP_PORT', 587 );
define( 'WPMS_SSL', 'tls' );
define( 'WPMS_SMTP_AUTH', true );
define( 'WPMS_SMTP_AUTOTLS', true );
define( 'WPMS_SMTP_USER', 'securessmtp' );
define( 'WPMS_SMTP_PASS', 'qcs_live_your_key_here' );

WPMS_ON must be true for WP Mail SMTP to use these values. Settings set here are greyed out on the settings page.

6. Send a test email

1. Go to WP Mail SMTP → Tools → Email Test, enter an address you can check and click Send Email.
2. WP Mail SMTP should report that the test email was sent. Check the inbox (and the spam folder the first time).
3. In the SecureSMTP dashboard, open the Email log. The test is listed with the source smtp, and its status changes to delivered once the receiving server accepts it.

Then submit one of your site’s forms to check a real notification end to end.

Troubleshooting

“Could not authenticate” or SMTP error 535

• The password must be the whole API key, starting with qcs_live_, with no spaces or line breaks.
• If the key was rotated in SecureSMTP, the old one stopped working at once. Paste the new key.
• If the site is disabled in SecureSMTP, logins are refused. See Blocks.

“SMTP connect() failed” or the test times out

Many hosts block outgoing SMTP ports. Switch to SSL with port 465 (or TLS with 587 if you started with 465). If both are blocked, use the SecureSMTP WordPress plugin instead: it sends over HTTPS, which hosts do not block.

A TLS or certificate error

Check that the encryption matches the port: TLS with 587, SSL with 465, and that Auto TLS is on. The host name must be exactly smtp.securessmtp.com.

The test is sent but never arrives

Look the email up in the SecureSMTP email log. It shows whether it was delivered, bounced or held, and why. Also check that the address is not on your suppression list.

More error messages and fixes: WP Mail SMTP not working? Common errors and how to fix them.

Frequently asked questions