SendTo & MailOptions pup up Save confirm dialog box

I have a form in an application that is working since ages and now I need to send a mail each time a new document is added or modified.I added two computed when composed fields named “SendTo” and “MailOptions” the first holding the recipient address and the second equal “1”.

When I save the document the unrequested Save confirm dialog box pups up while the mail is sent.

I also noticed that my saved and mailed document contains several new fields (DeliveryPriority, Recipients, PostedDate,…) that might be the reason for the confirmation request.

I wish I could keep my document “clean” and my users free from Save confirmation dialog box…

What have I to do?