6 files declare their use of MailFormatHelper in Drupal 9
- ContactSitewideTest.php in core/
modules/ contact/ tests/ src/ Functional/ ContactSitewideTest.php - HtmlToTextTest.php in core/
modules/ system/ tests/ src/ Functional/ Mail/ HtmlToTextTest.php - MailFormatHelperTest.php in core/
tests/ Drupal/ Tests/ Core/ Mail/ MailFormatHelperTest.php - MailTest.php in core/
modules/ system/ tests/ src/ Kernel/ Mail/ MailTest.php - PhpMail.php in core/
lib/ Drupal/ Core/ Mail/ Plugin/ Mail/ PhpMail.php - TestHtmlMailCollector.php in core/
modules/ system/ tests/ modules/ mail_html_test/ src/ Plugin/ Mail/ TestHtmlMailCollector.php