This doesn't apply to Google Workspace addresses that most small businesses will be using.
A lot of small businesses actually have a free address for legacy purposes. Send as, even for paid users, won’t support third-party providers.
This is incorrect. The plan doesn't apply to workspace aliases, but it does apply to workspace users using Send-As via SMTP.
A lot of small businesses actually have a free address for legacy purposes. Send as, even for paid users, won’t support third-party providers.