一直都是在user 的.profile把mail forward到gmail去
可是最近突然發現有些mail沒收到
check了一下mail log
發現以下的訊息

Mar  6 16:48:26 mail postfix/smtp[31508]: 206879E074E: to=<test@staff.edu.tw>, orig_to=<test2@mail.edu.tw>, relay=ASPMX.L.GOOGLE.COM[74.125.23.26]:25, delay=2, delays=0.01/0.01/0.54/1.4, dsn=5.7.1, status=bounced (host ASPMX.L.GOOGLE.COM[74.125.23.26] said: 550-5.7.1 [1.1.1.1      12] Our system has detected that this message is 550-5.7.1 likely unsolicited mail. To reduce the amount of spam sent to Gmail, 550-5.7.1 this message has been blocked. Please visit 550-5.7.1 http://support.google.com/mail/bin/answer.py?hl=en&answer=188131 for 550 5.7.1 more information. x1si13668566pdp.46 - gsmtp (in reply to end of DATA command))

居然被google視為spam而擋了
找了一下解決方法有三個 SPF DKIM DMARC
最快的是設定SPF
https://support.google.com/a/answer/178723?hl=zh-Hant

參考以下資料設定完成後
http://www.icst.org.tw/ArticlesDetail.aspx?seq=1351&lang=zh

目前沒有再出現被擋的訊息了
持續觀察中

不知道是不是太多人設forward了
XD