Hello Luca:
Excellent question. I will add this answer to FAQ in next version of Quick Mail.
You should be able login to your email account and find emails in “Sent Mail.”
If you have any delivery or reporting problems, you can fix them by installing the free Mailgun email delivery service. Quick Mail will use Mailgun plugin settings.
You must edit DNS records to use Mailgun, but it works perfectly. You can login to Mailgun to view sent mail, after installation.
Best wishes,
Mitchell