You can add the X-Priority header field and give it the value string "1″. For example: email.AddHeaderField "X-Priority","1″ This is the most common way of setting the priority of an email. "3″ is normal, and "5″ is the lowest. "2″ and "4″ are in-betweens, and frankly I’ve never seen anything but "1″ or "3″ used. Microsoft Outlook adds these header fields when setting a message to High priority:
X-Priority: 1 (Highest)
X-MSMail-Priority: High
Importance: High
I don’t think you’ll need all three, but you can add them all if you wish. My recommendation is to only add the X-Priority header.
Examples:
ASP: Set the X-Priority Header of an Email
SQL Server: Set the X-Priority Header of an Email
C#: Set the X-Priority Header of an Email
C++: Set the X-Priority Header of an Email
Delphi: Set the X-Priority Header of an Email
Visual FoxPro: Set the X-Priority Header of an Email
Java: Set the X-Priority Header of an Email
Perl: Set the X-Priority Header of an Email
Python: Set the X-Priority Header of an Email
Ruby: Set the X-Priority Header of an Email
VB.NET: Set the X-Priority Header of an Email
Visual Basic: Set the X-Priority Header of an Email
VBScript: Set the X-Priority Header of an Email
