The current SMTP custom configuration does not allow to specifiy a sender name but just a sender email address. So the From-field looks like
From: my.name@my.domain
With sender name, it would look like
From: Sender Name <my.name@my.domain>
The configuration dialog does not accept such input, an extra input field is missing.
An (optional) sender name could improve much the the mail input - showing the message comes from my Qnap - and not from my mail gateway email address.