Warning on Transaction Time

[EmaX093]

I ran a test in mxtoolbox.com and everything it's OK, but there's a warning about Transaction Time:

I'm curious to know if this is a expected behavior like Tarpitting or is something I can tune in the configuration? Certainly my mail server is not under heavy load 😂

[mdecimus]

Try disabling the SPAM filter, it might be that the DNS queries required to run the filter are taking too long.

[lic0san]

Trying to troubleshoot the same issue with MXtoolbox, I figured out that the slow transaction was due to some "Error Wait" delay (in Settings > SMTP > Inbound > RCPT Stage > Recipient Errors > Error Wait) which was defaulting to 5s. Lowering it down to 1s immediately made my server "Good on transaction time" according to MXtoolbox...