Your inbox is full of things you never asked for. An email company sits in the middle and can filter, bury, or bounce a message before you see it.
Gnesi does not do that to a message you allowed. You decide who can reach you, and what a business pays for the chance to be accepted. A friend at $0 is not competing with a promotion for a place in a filtered folder.
If you accept, you talk. If you don't, they go away. There is no leftover pile of messages you never agreed to open.
If the other person is not on Gnesi, you still do not hand them the message through their email company. They get a short invite in the mail client they already have. The message waits on Gnesi until they join. When they switch to the Gnesi app, that history is already here.