'''Failed to post message: Message content failed to pass security filters'''
Ensure you do not have any special characters in the message text that could fail the Booking.com Security checks. (For example do not use @ in the message text).
'''Message failed to send to reservation 12345678 - content or attachment is required'''
There are two possible reasons:
1. There is no content in the language of the Guest, in the Messaging tab of the auto action that you triggered for this booking.
*Open the booking go to the Mail & Action tab and check the guest language.
*Open the auto action and ensure you have text in the Subject, Plain Text Field and HTML Field.
2. Auto action should not send a message to the guest, go to the Messaging tab in the Auto action and set 'Sending Message' = NO (or Internal)
'''You cannot mark credit card as invalid since the property has not passed trust verification checks'''