In Avaza, when you send invoices to clients, the invoice email is officially sent from an Avaza domain. You can ask clients to whitelist this email address as well.
Figure: A Sample Invoice Email sent from Avaza
We do this to reduce the risk of these emails being considered spam. However, these emails are shown to be sent on your behalf, and when the customer replies, they are also replying directly to your email address.
Figure: The “reply-to” is set to User’s Email Address
You can ask your customers to whitelist “firstname.lastname@example.org” so invoice emails are sent straight to their inbox. For a detailed list of email addresses Avaza uses, please refer to this guide.