For inbound emails, the MTA of EMS will reconnect using the following formula:
300s (first try), 300*2 (second try), 600*2 (third try) until 4000s in 10 days.
For outbound emails, the MTA of EMS will reconnect using the following formula:
300s (first try), 300*2 (second try), 600*2 (third try) until 4000s in 1 day.