【求助】关于EMOS1.5邮件服务器收不到附件的问题

[雪域幽泉]

邮件服务器平台是EMOS1.5，基于CentOS，发送者发送到外网带附件的邮件，同时抄送给同域名的用户，外网用户可以收到附件，但是抄送的那几个人都没有收到附件，查看日志文件，没有什么问题。
发送者：[e-mail]
接受者：[e-mail]，
抄送：[e-mail]，[e-mail]，[e-mail]

相关的日志文件内容如下：
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Aug 23 17:31:01 mailserver postfix/smtpd[14335]: connect from unknown[xxx.xxx.xxx.xxx]
Aug 23 17:31:01 mailserver postfix/smtpd[14335]: DC3D23730593: client=unknown[xxx.xxx.xxx.xxx], sasl_method=LOGIN, sasl_username=[e-mail]
Aug 23 17:31:02 mailserver postfix/cleanup[15010]: DC3D23730593: message-id=<007e01d43ac4$1b377f90$51a67eb0$@[e-mail]>
Aug 23 17:31:04 mailserver postfix/qmgr[4363]: DC3D23730593: from=<[e-mail]>, size=1503631, nrcpt=4 (queue active)
Aug 23 17:31:04 mailserver pop3d-ssl: Connection, ip=[::ffff:xxx.xxx.xxx.xxx]
Aug 23 17:31:04 mailserver pop3d-ssl: LOGIN, user=[e-mail], ip=[::ffff:xxx.xxx.xxx.xxx], port=[56929]
Aug 23 17:31:05 mailserver pop3d-ssl: LOGOUT, user=[e-mail], ip=[::ffff:xxx.xxx.xxx.xxx], port=[56929], top=0, retr=0, rcvd=12, sent=39, time=1, stls=1
Aug 23 17:31:05 mailserver postfix/smtpd[15020]: connect from mailserver[127.0.0.1]
Aug 23 17:31:05 mailserver postfix/smtpd[15020]: 2A22A37305A0: client=mailserver[127.0.0.1]
Aug 23 17:31:05 mailserver postfix/cleanup[15010]: 2A22A37305A0: message-id=<007e01d43ac4$1b377f90$51a67eb0$@[e-mail]>
Aug 23 17:31:05 mailserver postfix/qmgr[4363]: 2A22A37305A0: from=<[e-mail]>, size=1504480, nrcpt=4 (queue active)
Aug 23 17:31:05 mailserver postfix/smtpd[15020]: disconnect from mailserver[127.0.0.1]
Aug 23 17:31:05 mailserver amavis[14123]: (14123-04) Passed CLEAN, [xxx.xxx.xxx.xxx] [xxx.xxx.xxx.xxx] <[e-mail]> -> <[e-mail]>,<[e-mail]>,<[e-mail]>,<[e-mail]>, Message-ID: <007e01d43ac4$1b377f90$51a67eb0$@[e-mail]>, mail_id: 1UrEyRsUOwhC, Hits: -0.772, size: 1503631, queued_as: 2A22A37305A0, 1637 ms
Aug 23 17:31:05 mailserver postfix/smtp[15011]: DC3D23730593: to=<[e-mail]>, relay=127.0.0.1[127.0.0.1]:10024, delay=4, delays=2.4/0/0/1.6, dsn=2.0.0, status=sent (250 2.0.0 Ok, id=14123-04, from MTA([127.0.0.1]:10025): 250 2.0.0 Ok: queued as 2A22A37305A0)
Aug 23 17:31:05 mailserver postfix/smtp[15011]: DC3D23730593: to=<[e-mail]>, relay=127.0.0.1[127.0.0.1]:10024, delay=4, delays=2.4/0/0/1.6, dsn=2.0.0, status=sent (250 2.0.0 Ok, id=14123-04, from MTA([127.0.0.1]:10025): 250 2.0.0 Ok: queued as 2A22A37305A0)
Aug 23 17:31:05 mailserver postfix/smtp[15011]: DC3D23730593: to=<[e-mail]>, relay=127.0.0.1[127.0.0.1]:10024, delay=4, delays=2.4/0/0/1.6, dsn=2.0.0, status=sent (250 2.0.0 Ok, id=14123-04, from MTA([127.0.0.1]:10025): 250 2.0.0 Ok: queued as 2A22A37305A0)
Aug 23 17:31:05 mailserver postfix/smtp[15011]: DC3D23730593: to=<[e-mail]>, relay=127.0.0.1[127.0.0.1]:10024, delay=4, delays=2.4/0/0/1.6, dsn=2.0.0, status=sent (250 2.0.0 Ok, id=14123-04, from MTA([127.0.0.1]:10025): 250 2.0.0 Ok: queued as 2A22A37305A0)
Aug 23 17:31:05 mailserver postfix/qmgr[4363]: DC3D23730593: removed
Aug 23 17:31:06 mailserver postfix/pipe[15021]: 2A22A37305A0: to=<[e-mail]>, relay=maildrop, delay=1, delays=0.74/0/0/0.3, dsn=2.0.0, status=sent (delivered via maildrop service)
Aug 23 17:31:06 mailserver postfix/pipe[15025]: 2A22A37305A0: to=<[e-mail]>, relay=maildrop, delay=1, delays=0.74/0.01/0/0.3, dsn=2.0.0, status=sent (delivered via maildrop service)
Aug 23 17:31:06 mailserver postfix/pipe[15023]: 2A22A37305A0: to=<[e-mail]>, relay=maildrop, delay=1, delays=0.74/0/0/0.3, dsn=2.0.0, status=sent (delivered via maildrop service)
Aug 23 17:31:06 mailserver postfix/smtpd[14335]: disconnect from unknown[xxx.xxx.xxx.xxx]
Aug 23 17:31:07 mailserver postfix/smtp[15022]: 2A22A37305A0: to=<[e-mail]>, relay=126mx02.mxmail.netease.com[yyy.yyy.yyy.yyy]:25, delay=2.6, delays=0.74/0/1/0.88, dsn=2.0.0, status=sent (250 Mail OK queued as mx37,0cmowEApIUzZfn5bbV_VFQ--.19655S2 1535016667)
Aug 23 17:31:07 mailserver postfix/qmgr[4363]: 2A22A37305A0: removed
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从日志上看，应该没有什么问题吧。
请问这可能是哪儿的原因呢？

[雪域幽泉]

通过web方式进入到邮箱，发现里面的附件都是winmail.dat，查网上的资料，都说是发件人的outlook设置的编码格式是RTF格式，应改成纯文本。这个还没有验证。但是以前很少出现这情况。
能不能从服务器这里修改？总不能要求发件人修改发送格式吧。本单位好说，外单位的就不好办了。