The Sender property specifies the SMTP sender. The Sender property is a shortcut to the Headers("X-Sender") collection item.
Set or returns a String value.
The Sender property must be formatted
using the user@domain format. It must not contain any display name such as
"Sender Name" <user@domain>
If the Sender property is not set, the Sender property will be initialized
using the email part of the From property.