Sometimes Voxie emails can sometimes be picked up as spam. The email comes from your email address. But because you are sending an email from you to you but not through your system (but instead through our server) some receiving email system will mark this as spam. Each system is different. There is no way to avoid this as the iPhone can not send an email with attachment directly from the phone. It must go through our server which creates the final email. We host this server at no cost to you.
The emails come from your email address so you should be able to whitelist your address so it's not picked up as spam. We do not believe it is the ad as we tested with and without and it was picked up by spam filters the same number of times. In other words, it's how the email is being sent, which is the ONLY way it can be sent with the iPhone's limitations.