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!