Issue #3262882 by AdamPS: Policy importing

drush.services.yml

...ler_bc/src/Plugin/EmailBuilder/SimplenewsEmailBuilder.php

.../Plugin/EmailBuilder/SimplenewsNewsletterEmailBuilder.php

src/Commands/MailerCommands.php

src/EmailFactory.php

src/Entity/MailerPolicy.php

src/MailerHelper.php

src/MailerHelperInterface.php

src/Processor/EmailAdjusterManager.php

src/Processor/EmailBuilderManager.php

src/Processor/EmailBuilderManagerInterface.php

src/Processor/MailerPolicyImportInterface.php

symfony_mailer.services.yml