Set e-mail priotity

Hello,

We are using SwiftMailer with our project, we wanted to set the priority in some special cases, which is quite easy to check with using the model, no problems there.

Then I noticed that it is possible to set, for example, the mail body, to and from using the function calls, even attachements. But not the priority, I got it done in the end by creating my own swift_message instance.

Was there any particular reason why this was not implement in any way in the default Yii classes? Myself and a colleague plan on building this into the default Yii2 swiftmailer class, but we where wondering if it was intentionally left out.

With kind regards,

Bob