Other mail systems should hopefully be configured for retry up to a few days. So I wouldn't think the mails should bounce unless someone used a really short re

Other mail systems should hopefully be configured for retry up to a few days. So I wouldn't think the mails should bounce unless someone used a really short retry period. "Retries continue until the message is transmitted or the sender gives up; the give-up time generally needs to be at least 4-5 days." from RFC 5321