9 files declare their use of SubscriptionInterface in Mailing List 8

AnonymousSubscriptionAccessForm.php in src/Form/AnonymousSubscriptionAccessForm.php

MailingListController.php in src/Controller/MailingListController.php

MailingListExportForm.php in src/Form/MailingListExportForm.php

MailingListImportForm.php in src/Form/MailingListImportForm.php

MailingListManager.php in src/MailingListManager.php

MailingListManagerInterface.php in src/MailingListManagerInterface.php

mailing_list.module in ./mailing_list.module

Contains the Mailing list module.

mailing_list_confirm.module in mailing_list_confirm/mailing_list_confirm.module

Contains the Mailing list confirm module.

Subscription.php in src/Entity/Subscription.php