MailGates 有灰名單功能,此功能除了檢查來源 IP,也會檢查寄件人及收件人資訊;



一般而言,郵件主機的 IP 應不會隨意更換,因此相同一封信件經過第一次寄送之後,會先被灰名單機制阻擋,

並告知對方主機稍後再重送 (451 System(g) busy, try again later.),

且 UI 管理頁面查詢該筆連線過濾結果會顯示 "暫時拒絕連線",

待對方主機重送後,信件的寄件人、收件人及來源 IP 仍都相同,MailGates 就可將信件收下。



/mailgates/mqueue/log/mgsmtpd.log:


System(g) busy

[2011/06/17 10:07:07] [127.0.0.16:9252-1] Connection initialized.
[2011/06/17 10:07:07] [127.0.0.16:9252-1] EHLO AD.lab.com
[2011/06/17 10:07:07] [127.0.0.16:9252-1] MAIL FROM:<user@lab.com> SIZE=1716
[2011/06/17 10:07:12] [127.0.0.16:9252-1] RCPT TO:<user@test.com>
[2011/06/17 10:07:12] [127.0.0.16:9252-1] DATA
[2011/06/17 10:07:12] [127.0.0.16:9252-1] Negative reply <451 System(g) busy, try again later.>
[2011/06/17 10:07:12] [127.0.0.16:9252-1] Read EOF,closing connection.
[2011/06/17 10:07:12] [127.0.0.16:9252-1] MGLOG [MGTAGLOG (RBL:2,PASS,0.000000e+00)(flag:2,DYNAMIC,RELAY:PASS)][from user@lab.com][to user@test.com][ret 451 System(g) busy, try again later.]
[2011/06/17 10:07:12] [127.0.0.16:9252-1] Connection closed.(5s.675424u)