While I dislike the feature getting removed, this argument does not hold up to scrutiny. They will remove using external SMTP servers to send emails from external, third-party addresses. Sending as another Gmail or Google Workspace address will continue to work, but that path is fully Google-internal.

Emphasis mine:

> You can continue to use "Send as" for any -->Google-hosted identities<--, including other Gmail addresses or aliases associated with your Google Workspace account. The discontinuation will not impact these addresses, which only applies to third-party, non-Google email accounts.*

> They will remove using external SMTP servers to send emails from external, third-party addresses.

What about using Gmail's own internal SMTP servers(i.e. smtp.gmail.com) to send emails from external, third-party addresses?