Public Function BeginSend ( _
	mail As MailMessage, _
	sender As String, _
	recipients As String, _
	callback As AsyncCallback, _
	state As Object _
) As IAsyncResult

public IAsyncResult BeginSend(
	MailMessage mail,
	string sender,
	string recipients,
	AsyncCallback callback,
	Object state
)

Return Value

If the sender address argument is null (Nothing in Visual Basic), it is taken from the from the "Sender" header field or from the first address in the "From" field if the "Sender" is missing.
If the sender address argument is empty string, it means null sender - same behavior as if "<>" would be specified.
If the recipients argument is null (Nothing in Visual Basic), it overrides the list of recipients contained in the message. If the recipients argument is null, the list of recipients is extracted from "To", "Cc" and "Bcc" header fields.
The "Bcc" field is removed from message headers prior to sending. Set the AllowNullSender property to allow sending a mail message without a sender specified.

In builds for .NET 4.0 and higher, this method is available as an extension method. Add 'using Rebex.Legacy' (C#) or 'Import Rebex.Legacy' (VB.NET) to your code in order to use it.

.NET Compact Framework