Mailster Gmail Integration

This plugin requires Mailster 2.4.11 or newer, PHP 8.1 or newer, and a Google account. You create an OAuth Client ID in Google Cloud (this is not an API key). Newsletter content is sent to Google through the Gmail API. The plugin requests the https://mail.google.com/ scope so it can send mail and read bounce messages in that mailbox. Gmail applies its own sending limits; Mailster’s guide notes that Gmail is a weak fit for large marketing lists.

• Gmail delivery method — Choose Gmail under Newsletter → Settings → Delivery.
• Google OAuth — Enter the OAuth Client ID and Client Secret, then authorize the Google account. The settings screen shows the redirect URI to paste into the Google Cloud client.
• Sending address — After authorization, saving settings copies the connected Gmail address into Mailster’s From, Reply-To, and Bounce fields.
• Gmail API sending — Mailster messages are sent with users.messages.send for the authorized user. Mailster’s own DKIM signing is turned off for these sends because Gmail handles authentication.
• Bounce handling — The addon checks that Gmail mailbox for delivery failures and “please remove me” replies, then unsubscribes or bounces the matching Mailster subscriber and removes those messages.
• Redirect URL filter — Developers can change the OAuth redirect with the mailster_gmail_redirect_url filter.

1. Install and activate Mailster Gmail Integration next to Mailster 2.4.11+.
2. In Google Cloud, enable the Gmail API and create an OAuth client (Web application). Add the redirect URI shown in Mailster’s Gmail settings.
3. Open Newsletter → Settings → Delivery, select Gmail, paste the Client ID and Client Secret, and save.
4. Click Authorize, allow access in Google, and return to Mailster.
5. Send a test email, then send Mailster campaigns through Gmail.

1. Upload the entire mailster-gmail folder to the /wp-content/plugins/ directory, or install it from the WordPress plugins screen.
2. Activate the plugin through the Plugins menu in WordPress.
3. Make sure Mailster 2.4.11 or newer is installed and active.
4. In Google Cloud, enable the Gmail API, configure the OAuth consent screen, and create a Web application OAuth client. Add the Authorized redirect URI from Mailster’s Gmail settings.
5. Go to Newsletter → Settings → Delivery, open the Gmail tab, enter the Client ID and Client Secret, and save.
6. Click Authorize, grant access to the Google account, and send a test email.

• changed: requires PHP 8.1 or newer

• fixed: composer packages with PHP 8.0+

• fixed: issue with third party library on PHP 8.0+
• added: mailster_gmail_redirect_url filter for redirect URL
• requires now PHP 7.4+

• Fixed some typo and updated method

• Update for Mailster 3.0

• initial release