Good afternoon Taweesak & Naret
After tracing the mail delivery from the affected address, messages sent by bookingonline@itcbangkok.com, are blocked by Office 365 spam filters as high spam content.
Attached is the report from our Exchange system.
Please have them send another email from that same address with different content (text) so that we can determine if it was blocked because of the sender address or the actual content.
It is most likely that it was due to the content, so this shouldn't occur again.
Thanks and Best Regards,