Even though mail servers may be configured to silently discard email, the SMTP RFC strongly discourages this Unless of course senders are acknowledged to get fraudulent or unwanted. For all other mail, the RFC suggests returning undeliverable mail using an error code. A/B tests – Just before sending out https://riveranuph.canariblogs.com/helping-the-others-realize-the-advantages-of-it-support-42114403