We're seeing some (maybe?) strange delays when submitting individual emails to our local Postfix server.

To help diagnose the issue, I wrote a little test program which sends 5 emails:

get smtp 1ms   (  1 ms)
email 0 677ms  (676 ms)
email 1 802ms  (125 ms)
email 2 890ms  ( 88 ms)
email 3 973ms  ( 83 ms)
email 4 1088ms (115 ms)

Discounting the handshaking in the first email, that's about 90ms per email. These timings have also been corroborated with another test app written by someone else using a different codepath, so it appears to be server related.

I turned on detailed logging and I can see that the delay is between the end of message \r\n\r\n and the receive:

[16:31:29.95] [SEND] \r\n.\r\n
[16:31:30.05] [RECV] 250 2.0.0 Ok: queued as B128E1E063\r\n

[16:31:30.08] [SEND] \r\n.\r\n
[16:31:30.17] [RECV] 250 2.0.0 Ok: queued as 4A7DE1E06E\r\n

[16:31:30.19] [SEND] \r\n.\r\n
[16:31:30.27] [RECV] 250 2.0.0 Ok: queued as 68ACC1E072\r\n

[16:31:30.28] [SEND] \r\n.\r\n
[16:31:30.34] [RECV] 250 2.0.0 Ok: queued as 7EFFE1E079\r\n

[16:31:30.39] [SEND] \r\n.\r\n
[16:31:30.45] [RECV] 250 2.0.0 Ok: queued as 9793C1E07A\r\n

The time intervals tell the story (discounting the handshaking required for the initial email) -- each email is waiting about 60-90 milliseconds for postfix to queue!

This seems .. excessive .. to me. Is it "normal" for postfix to take 60-90 ms for every email you send it? Or do I just have unreasonable expectations? I would expect the local postfix server to queue the email in about 20ms, tops!