SimplyBook.me has launched a new SMTP extra feature (plugin). It allows you to use your own SMTP server so all email sent from the SimplyBook.me system on your behalf, comes from your own email address. Remark that if you have a gmail address or g-suite email, you can send up to 1.000 emails per day through that address.
You can store a copy of outgoing emails in your Gmail but you need to log into your Gmail or Google Apps email Settings and Click on the Forwarding/IMAP tab and scroll down to the IMAP Access section. Then please set the IMAP as enabled in order for emails to be properly copied to your sent folder. For added security, setup double authentication for the email that you plan to use. If you send more than 1.000 notifications/promotions per day, you can look at other smtp services like sendinblue.com, sendgrid.com, mailjet.com, or authsmtp.com.