### Fixed:

- Setup Wizard steps navigation, when going backwards.

### Fixed:

- The check if `wp_mail` function is overwritten on Windows servers.

### Changed:

- Removed MailPoet from the list of conflicting plugins.

### Fixed:

- PHP warning for undefined variable when using the Default (none) mailer.

### Added:

- Alerts for failed emails (Email, Slack, SMS, and Webhook notifications).

- Check if `wp_mail` function is overwritten.

- DB table (`wpmailsmtp_tasks_meta`) cleanup after scheduled actions execution. Keeps DB size small.

### Changed:

- Updated the list of conflicting plugins (added Branda and MailPoet).

- Improved WP Site Health license check.

- Improved Outlook mailer authorization flow error handling.

- Updated Action Scheduler library to 3.4.2.

- Improved Amazon SES (added support for V2 client).

### Fixed:

- SMTP.com mailer email content-encoding.

- Amazon SES long Return-Path header encoding.

- Dashboard widget graph when there is no email logs data.

- Email Log retention period cleanup task DB table check.

- Missing Sendinblue email body WP filter.

- Chart.js library conflicts with other plugins.

### Added:

- New transactional mailer: SendLayer integration.

- Support for changing From Email address in Outlook mailer (Send As, Shared Mailboxes, and Groups).

- Support for bigger attachments in Outlook mailer.

### Changed:

- Improved Mailgun API error message extraction.

- Standardized error messages format and improved WP remote request errors extraction.

### Fixed:

- Lite plugin uninstall actions clearing plugin options while Pro version is active.

- Amazon SES identities verification data retrieval for more than 100 identities.

- Hiding unrelated network admin notices on WP Mail SMTP pages.

### IMPORTANT

- Support for WordPress versions 5.1.x or lower has been discontinued. If you are using one of those versions, you MUST upgrade WordPress before installing or upgrading to WP Mail SMTP v3.3. Failure to do that will disable WP Mail SMTP functionality.

### Added:

- Email Log: sent status verification AS tasks for Postmark and SparkPost.

- New Amazon AWS SES region: Osaka.

- PHP 8.1 compatibility.

### Changed:

- Email Log: improved sent status verification accuracy with webhooks for: SMTP.com, Sendiblue, Mailgun, Postmark and SparkPost.

- Updated the list of conflicting plugins (added FluentSMTP and WP HTML Mail).

- Domain verification process for AWS SES mailer (now using DKIM verification instead of the simple TXT record verification).

- Improved debug error message for the Other SMTP mailer in Debug Events.

- Updated Action Scheduler library to 3.4.0.

- Improved Action Scheduler performance.

### Fixed:

- PHP deprecated notices in Sendinblue library (PHP 7.4+).

- Email Log: resend issue with incorrectly stored headers.

- Non-network admin was allowed to change the Debug Event setting, if network-wide setting was enabled.

- DB tables row in Site Health Info section is now private.

- Debug Events' screen options visible on general Tools page.

- Screen Options right alignment.

### Fixed:

- PHP 8 compatibility when existing Gmail mailer connection is revoked.

### Added:

- New transactional mailer: SparkPost integration.

- One-click migration from FluentSMTP plugin.

- Plugin constants integration in Setup Wizard.

### Fixed:

- Early plugin deactivation issue with activity log plugins.

### Added:

• - New transactional mailer: Postmark integration.
• - Email Log: added CC and BCC columns to the table.
• - Support for string attachments (added via PHPMailer object).

### Changed:

• - Improved Weekly Email Summary Setup Wizard control.
• - Improved Email Source detection in Debug Events and Email Log for WP Core sent emails.
• - Improved uninstall process. It now removes all plugin DB data and tables.

### Fixed:

• - Email Source detection in Debug Events and Email Log for file paths with backslashes.
• - Amazon SES automatic closest region detection (keycdn API request).
• - Added SSL check for Amazon SES and Outlook mailers in the Setup Wizard.
• - Blurry image assets in Weekly Email Summary.
• - PHP extension mb_strings not polyfilled correctly.
• - New user registration email template for Email Controls feature.
• - Added missing is_email_sent filters for Sendinblue, Mailgun, and Gmail mailers.
• - Debug Events double-entry DB save, because of a bug in is_email_sent method for certain mailers.
• - Network subsite switcher in WP Multisite installations with subdomain configuration.

### Fixed:

- Fatal PHP error on WP version 5.2 and lower (missing wp_timezone function).