Deprecation of Email V1 began almost two years ago and beginning with the March maintenance release to London & Netherlands subscriptions on March 17th, 2021 and all other subscriptions on March 19th, 2021, all API support for V1 emails will be ended. After this release, any attempts to interact with V1 emails via the Asset APIs will result in errors and no actions taken. All known remaining users since February 24th, 2021 have been notified, but it is possible that there are still integrations which may attempt to interact with these assets. The most common types of affected integrations are services which offer digital asset management, translation, and localization.
If you do observe integration failures as a result of this change, you will still be able to upgrade problematic assets by editing and approving them. Once an email asset is upgraded to V2, you should be able to resume using it with integrated services.