This article was previously published under Q313318
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Clients that are outside an ISA server cannot relay mail through that ISA server. This problem may occur if external clients try to send mail to other external recipients.
The internal mail server may require client authentication with the AUTH command. This functionality is not supported by the Simple Mail Transfer Protocol (SMTP) application filter in the original release of Microsoft ISA Server.
A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language. The global version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
Date Time Version Size File name---------------------------------------------------------22-Oct-2002 14:25:24 3.0.1200.180 60,176 Fltrsnk1.dll22-Oct-2002 14:25:28 3.0.1200.180 93,968 Smtpfltr.dll
Microsoft has confirmed that this is a problem in Internet Security and Acceleration Server 2000.