On February 18th, 2020 between 11:00-11:30 (UTC) we will change the certificate of api.messagebird.com. This is regarding our old HTTP-API service hostname, not our REST-API service.
Though the vast majority of applications will not be impacted in any way, there is a possibility that some applications are performing a comparison of the certificate with a local copy. Please update your local copy at the same time we update the certificate. A copy of the certificate can be found here: http://www.messagebird.com/download/certificates/messagebird-com-2017-2020.crt