When you click a hyperlink that uses a "Mailto" Uniform Resource Locator (URL) with a recipient list that exceeds 260 characters, a truncated address list may be created in the e-mail program that is started (such as Microsoft Outlook or Microsoft Outlook Express).

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This is a Windows NT 4.0 limitation. The URL is passed to a Windows NT 4.0 shell function (ShellExecute) to create a process for the mail client to run under. The Shell function passes the address list as a parameter and the variable used for that parameter is declared as a fixed size buffer (260 bytes). When the mail client is started and the address list is passed as a parameter, the address list is limited to 260 bytes.

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One possible workaround is to place the members of the recipient list in a distribution list and reference the distribution list alias in the "Mailto" URL.

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Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

This issue does not occur in Microsoft Windows 2000.

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