public bool RenameFolder(
	string oldName,
	string newName
)

Public Function RenameFolder ( 
	oldName As String,
	newName As String
) As Boolean

// To use the code below, import MailBee namespaces at the top of your code
using MailBee;
using MailBee.ImapMail;

// The actual code (put it into a method of your class)
Imap imp = new Imap();

// Connect to the server and log in the account.
imp.Connect("imap4.company.com");
imp.Login("jdoe@company.com", "secret");

// First, check if "Sent" exists and "Sent Items" does not exist. To
// determine this, we'll will get the list of root level folders only
// (we could have received all the folders, but it's more effecient
// to download only root ones since we're going to rename a root level
// folder into another root level name).

string sentFolderName = null;
bool isSentItems = false;
FolderCollection folders = imp.DownloadFolders(false, string.Empty, "%");

foreach (Folder imapFolder in folders)
{
    string folderName = imapFolder.Name.ToLower();
    if (folderName == "sent")
    {
        sentFolderName = imapFolder.Name;
    } 
    else if (folderName == "sent items")
    {
        isSentItems = true;
    }
}

if (sentFolderName == null)
{
    Console.WriteLine("Sent folder does not exist.");
}
else if (isSentItems)
{
    Console.WriteLine("'Sent Items' folder already exists.");
}
else
{
    imp.RenameFolder(sentFolderName, "Sent Items");
    Console.WriteLine(sentFolderName + " renamed to 'Sent Items'.");
}

imp.Disconnect();

' To use the code below, import MailBee namespaces at the top of your code
Imports MailBee
Imports MailBee.ImapMail

' The actual code (put it into a method of your class)
Dim imp As New Imap

' Connect to the server and log in the account.
imp.Connect("imap4.company.com")
imp.Login("jdoe@company.com", "secret")

' First, check if "Sent" exists and "Sent Items" does not exist. To
' determine this, we'll will get the list of root level folders only
' (we could have received all the folders, but it's more efficient
' to download only root ones since we're going to rename a root level
' folder into another root level name).

Dim sentFolderName As String = Nothing
Dim isSentItems As Boolean = False
Dim folders As FolderCollection = _
    imp.DownloadFolders(False, String.Empty, "%")

For Each imapFolder As Folder In folders
    Dim folderName As String = imapFolder.Name.ToLower()
    If folderName = "sent" Then
        sentFolderName = imapFolder.Name
    ElseIf folderName = "sent items" Then
        isSentItems = True
    End If
Next

If sentFolderName Is Nothing Then
    Console.WriteLine("Sent folder does not exist.")
ElseIf isSentItems Then
    Console.WriteLine("'Sent Items' folder already exists.")
Else
    imp.RenameFolder(sentFolderName, "Sent Items")
    Console.WriteLine(sentFolderName & " renamed to 'Sent Items'.")
End If

imp.Disconnect()