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Reconnecting WordPress SMTP Plugins

Learn how to easily update your WordPress SMTP plugins after your email migration to ensure your website continues to send emails reliably.

Niko Baumgartl avatar
Written by Niko Baumgartl
Updated this week

To ensure your WordPress website continues to send emails (e.g., contact form inquiries or order confirmations) without interruption, you must update the SMTP data in your WordPress backend following the email migration.

In this guide, we will show you how to adjust the configuration for two popular plugins: WP Mail SMTP and Post SMTP.

The good news: Your sender address and username remain unchanged. You only need to replace the hostname and your password within the plugin.

💡 Note: If you use a different SMTP plugin, don't worry – the principle and the data to be entered are identical for almost all SMTP plugins.

Comparison: What has changed?

As part of the migration, the server name and your password have changed. Please use only the following new data from now on:

Setting

Old Data

New Data

SMTP Host

smtp.mailbox.org

smtp-rb.securemail.pro

Port

587

587

Encryption

TLS / STARTTLS

TLS / STARTTLS

Authentication

Password

Password

Password

Your old password

Your NEW password

1. Updating WP Mail SMTP

  1. Log in to your WordPress backend.

  2. In the left-hand menu, navigate to WP Mail SMTP -> Settings.

  3. Scroll down to the Mailer section. "Other SMTP" should be selected here.

  4. Replace the old entry under SMTP Host with: smtp-rb.securemail.pro.

  5. Ensure that Encryption is set to TLS and the Port is set to 587.

  6. Enter your new password under SMTP Password.

  7. Click Save Settings.

Error Log in WP Mail SMTP

If the email delivery does not work, click on the Email Test tab at the top and send a test email. If it fails, an error message will appear.

  • Click "View Full Error Log" in the error message.

  • Here you can see exactly whether, for example, the password was incorrect (Authentication failed) or the host could not be reached.

2. Updating Post SMTP

  1. Go to Post SMTP -> Settings in your WordPress backend.

  2. In the Connection tab under Transport Settings, replace the old hostname with: smtp-rb.securemail.pro.

  3. Check that the Port is set to 587 and the type is set to STARTTLS.

  4. Update your Password in the corresponding field.

  5. Click Save Changes.

Error Log in Post SMTP

Post SMTP has one of the best built-in logging systems:

  • In the left-hand menu, click on Post SMTP -> Email Log.

  • Here you will see a list of all sent (and failed) emails.

  • Hover over a red entry (Status: Failed) and click on Session Log. This shows you in detail what the server reported during the connection attempt.

Troubleshooting: If it still doesn't work

If the test delivery fails, please check the following points:

  1. Password Check: Did you reset your password in the Raidboxes Dashboard after the migration? The old mailbox.org password will no longer work.

  2. Security Plugins: Some security plugins block outgoing connections. Try deactivating them temporarily for testing.

  3. Typos: Pay close attention to the hostname smtp-rb.securemail.pro. A misplaced dot or hyphen will prevent the connection.

If you continue to have issues, please send us a screenshot of the error log from your SMTP plugin so we can assist you quickly.

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