我们在使用 exim 时遇到了一些中间问题，有些电子邮件可以顺利通过，而其他电子邮件却收到“550 无法从指定地址接收”错误。
这是我们用来设置 EXIM 的指南： https://sendgrid.com/docs/Integrate/Mail_Servers/exim.html
现在，这是我的 exim_mainlogs 文件中的 exigrep。请注意，这里有一堆 Completed QT=1s 消息，但中间随机出现一条 Uauthenticated senders not allowed（未经身份验证的发件人不允许）。看起来 sendgrid 处理得很好，但随后出错并随机返回身份验证错误，尽管我们每次都发送正确的凭据。
[root@dulce log]# exigrep "Re: Scanner and Printing System" exim_mainlog | more
2014-07-09 12:06:29 [14711] 1X4uO5-0003pH-2f <= [email protected] H=cpe-74-71-193-253.nyc.res.rr.com ([192.168.0.6]) [74.71.193.253]:49427 I=[162.242.1
52.138]:25 P=esmtpsa X=TLSv1:AES128-SHA:128 CV=no SNI="dulce.45press.com" A=dovecot_plain:[email protected] S=6560 M8S=0 id=D9563BCF-9506-4384-AD7E-CC6
[email protected] T="Re: Scanner and Printing System" from <[email protected]> for [email protected]
2014-07-09 12:06:30 [14725] 1X4uO5-0003pH-2f => [email protected] F=<[email protected]> P=<[email protected]> R=send_via_sendgrid T=sendgrid_
smtp S=6701 H=smtp.sendgrid.net [198.37.144.212]:587 X=UNKNOWN:DHE-RSA-AES256-GCM-SHA384:256 CV=no DN="/OU=Domain Control Validated/CN=*.smtp.sendgrid.net" A
=sendgrid_login C="250 Delivery in progress" QT=1s DT=1s
2014-07-09 12:06:30 [14725] 1X4uO5-0003pH-2f Completed QT=1s
2014-07-09 13:25:31 [3099] 1X4vcZ-0000nz-HE <= [email protected] H=cpe-74-71-193-253.nyc.res.rr.com ([192.168.0.6]) [74.71.193.253]:52929 I=[162.242.15
2.138]:25 P=esmtpsa X=TLSv1:AES128-SHA:128 CV=no SNI="dulce.45press.com" A=dovecot_plain:[email protected] S=15739 M8S=0 id=D21395E7-6DB1-4F8A-8965-CE3
[email protected] T="Re: Scanner and Printing System" from <[email protected]> for [email protected]
2014-07-09 13:25:32 [3104] 1X4vcZ-0000nz-HE ** [email protected] F=<[email protected]> P=<[email protected]> R=send_via_sendgrid T=sendgrid_s
mtp: SMTP error from remote mail server after MAIL FROM:<[email protected]> SIZE=17027: host smtp.sendgrid.net [198.37.144.225]: 550 Cannot receive fro
m specified address <[email protected]>: Unauthenticated senders not allowed
2014-07-09 13:25:32 [3104] 1X4vcZ-0000nz-HE Completed QT=1s
2014-07-09 16:12:30 [18055] 1X4yEA-0004hD-4T <= [email protected] H=cpe-74-71-193-253.nyc.res.rr.com ([192.168.0.6]) [74.71.193.253]:62575 I=[162.242.1
52.138]:25 P=esmtpsa X=TLSv1:AES128-SHA:128 CV=no SNI="dulce.45press.com" A=dovecot_plain:[email protected] S=29598 M8S=0 id=7D4EC3BF-A30B-40EA-886B-FD
[email protected] T="Re: Scanner and Printing System" from <[email protected]> for [email protected]
2014-07-09 16:12:31 [18061] 1X4yEA-0004hD-4T => [email protected] F=<[email protected]> P=<[email protected]> R=send_via_sendgrid T=sendgrid_
smtp S=30117 H=smtp.sendgrid.net [198.37.144.212]:587 X=UNKNOWN:DHE-RSA-AES256-GCM-SHA384:256 CV=no DN="/OU=Domain Control Validated/CN=*.smtp.sendgrid.net"
A=sendgrid_login C="250 Delivery in progress" QT=1s DT=1s
2014-07-09 16:12:31 [18061] 1X4yEA-0004hD-4T Completed QT=1s
2014-07-09 16:40:27 [23323] 1X4yf7-00064B-IP H=hallogram.com [128.121.218.188]:49302 I=[162.242.152.138]:25 Warning: "SpamAssassin as haroldga detected messa
ge as NOT spam (3.9)"
2014-07-09 16:40:27 [23323] 1X4yf7-00064B-IP <= [email protected] H=hallogram.com [128.121.218.188]:49302 I=[162.242.152.138]:25 P=esmtps X=TLSv1:EDH-RSA
-DES-CBC3-SHA:168 CV=no S=30591 M8S=0 [email protected] T="RE: Scanner and Printing System" from <[email protected]> for j
[email protected]
2014-07-09 16:40:27 [23327] 1X4yf7-00064B-IP => jocelyn <[email protected]> F=<[email protected]> P=<[email protected]> R=virtual_user T=virtua
l_userdelivery S=30711 QT=6s DT=0s
2014-07-09 16:40:27 [23327] 1X4yf7-00064B-IP Completed QT=6s
Sendgrid 说这是 exim 的问题，但我不太确定，因为有些电子邮件可以正常发送，有些则不行。有人知道该去哪里找吗？
答案1
您提供的信息非常少，不足以准确调试问题，但我可以做出一些有根据的猜测并提供一些可以查看的地方。
您确定失败的尝试是连接到 smtp.sendgrid.com:587 吗？这就像您的 exim 连接到端口 25，并且没有使用用户/密码来尝试发送，而 sendgrid 拒绝了它。
这很可能是在他们的后端，他们在一系列 LDAP 服务器上对身份验证进行负载平衡，其中一个服务器拥有您的用户的陈旧信息，或者其中一个服务器达到资源限制并开始拒绝或超时新的身份验证尝试。
确保您的系统没有达到资源限制并且用户/密码查找失败。
查明是否有其他人遇到 smtp.sendgrid.com:587 的定期身份验证问题。
当您在原始问题中提供更多调试信息时，我会补充这个答案，希望我们能够共同努力找到最终的解决方案。