Why’s that even relevant if the recipient is the wrong address? Email isn’t particularly secure anywhere, and gmail has forwarding and IMAP and aliases and other services that send emails outside of gmail. But sending sensitive documents to the wrong recipient, which was the topic that started this sub-thread, is a case where it does not matter how secure your servers are.
Sure it is, and your own comment above about gmail to gmail being fairly secure demonstrated that. Using a photocopier is intentional, and everyone knows what a photocopier is. Most people don’t know what IMAP is, and an email sender does not know if the recipient uses IMAP.
And this is still irrelevant to sending email to the wrong recipient, so I don’t know why you’re stuck on infra security.
