alt Hacker News> retried 1/2/4/8 Minuten apart
That's generally not very clever, as it will impose an unneeded burden on a receiving server which actually has temporary resource problems, and it will collide with greylisting, for example.
RFC 5321 states in section "4.5.4.1. Sending Strategy" that the retry interval should be at least 30 minutes, while the give-up time needs to be at least 4–5 days: