Why is my email being sent from firstname.lastname@example.org?
If you are getting e-mail notices from Booking Manager from email@example.com instead from the actual e-mail address you are using, that means that you have Sender Policy Framework (SPF) record defined in your domain settings (DNS).
SPF is a useful security feature that identifies which email servers are allowed to send email on your behalf, and prevents unauthorized servers, such as spammers to send emails in your name.
If your DNS settings have this feature and Booking Manager server is not allowed to send emails in your name, it will be sent from firstname.lastname@example.org to ensure uninterrupted the delivery of notifications.
In order to allow e-mails to be send on your behalf you need to allow Booking Manager mail servers. To do that add following text to your existing SPF DNS record:
Example of one full SPF record for GMail users:
v=spf1 a mx include:spf.booking-manager.com include:_spf.google.com ~all
For more detailed information you can read
Multiple SPF records are not allowed
Common mistake when setting up additional SPF servers in your DNS settings is to add a new record instead of changing the existing one. Only one SPF record is allowed. You can read more detailed explanation here: https://support.google.com/a/answer/4568483?hl=en