How to handle delays and greylisting patterns?

Handling greylisting and delays:

What greylisting is:

Temporary rejection asking sender to retry later

Spam bots often do not retry

Legitimate servers do retry

Normal behavior:

Initial delay (minutes to hours)

Automatic retry succeeds

Subsequent emails faster (cached)

When delays are concerning:

Increasing delay frequency

New greylisting where none existed

Combined with other issues

Investigation:

Check if new IP triggering greylisting

Verify retry behavior is working

Consider IP reputation causing increased scrutiny

Brief inspections are normal. Prolonged delays indicate increased suspicion.