Hi,
I have checked the our document, I think there is no limitation with
MailMessage class in the System.Web.Mail Namespace.
Because we have no make such test that sends mail to such a large group of
recipients for one time, I can not 100 percent guarantee if it will work on
all kind of environment. Usually, the To property is a string type, its
limitation should be concern of the available memory of the computer.
Also here is KB article about a known issue the SMTP mail message, it has
been fixed in the Windows 2000 sp3.
294379 Addressees Appear in Body of SMTP Message Instead of the Header If
You
http://support.microsoft.com/?id=294379
Best regards,
Peter Huang
Microsoft Online Partner Support
Get Secure! -
www.microsoft.com/security
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