How to: Programmatically search within a specific folder
Applies to: 
Visual Studio 
Visual Studio for Mac
Note
This article applies to Visual Studio 2017. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here
This code example uses the Find and FindNext methods to search for text in the subject field of e-mail messages that are in the Inbox. This method uses a string filter to check for the letter T as the starting letter of the Subject text.
Applies to: The information in this topic applies to VSTO Add-in projects for Outlook. For more information, see Features available by Office application and project type.
Example
private void SearchInBox()
{
Outlook.Folder inbox = this.Application.ActiveExplorer().Session.
GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox);
Outlook.Items items = inbox.Items;
Outlook.MailItem mailItem = null;
object folderItem;
string subjectName = string.Empty;
string filter = "[Subject] > 's' And [Subject] <'u'";
folderItem = items.Find(filter);
while (folderItem != null)
{
mailItem = folderItem as Outlook.MailItem;
if (mailItem != null)
{
subjectName += "\n" + mailItem.Subject;
}
folderItem = items.FindNext();
}
subjectName = " The following e-mail messages were found: " +
subjectName;
MessageBox.Show(subjectName);
}