1MX needs 19 seconds to relay 100 messages with one recipient. 2smtp/smtpd process limit = 100, bundle_recipients = 0. 3 4/usr/bin/time ./smtp-source -s 5 -m 100 fist 5 9.56 real 0.07 user 0.20 sys 6Jun 8 14:33:19 fist mx:smtpd[19366]: connect from spike.porcupine.org(168.100.1 7Jun 8 14:33:36 fist mx:smtp[19382]: 085781: to=<foo@spike.porcupine.org>, relay 8Total time: 17 seconds 9 10/usr/bin/time ./smtp-source -s 10 -m 100 fist 11 8.95 real 0.12 user 0.19 sys 12Jun 8 14:34:22 fist mx:smtpd[19377]: connect from spike.porcupine.org(168.100.1 13Jun 8 14:34:41 fist mx:smtp[19378]: 085792: to=<foo@spike.porcupine.org>, relay 14Total time: 19 seconds 15 16/usr/bin/time ./smtp-source -s 20 -m 100 fist 17 9.79 real 0.11 user 0.27 sys 18Jun 8 14:35:18 fist mx:smtpd[19377]: connect from spike.porcupine.org(168.100.1 19Jun 8 14:35:38 fist mx:smtp[19382]: 085794: to=<foo@spike.porcupine.org>, relay 20Total time: 20 seconds 21