Do you use SMTP for sending via Postmark, and still use TLSv1.0 for authentication? If so, please read on, because we are making some changes to make this endpoint more secure, and they will affect you.
The most significant change is that we are disabling TLSv1.0 on February 1, 2020. This protocol is old and vulnerable, so we will be rejecting connection requests that use TLSv1.0. For additional information on how to test to make sure your sending will continue uninterrupted, or to contact our team for assistance, head over to this post.
Please note that these changes will only affect sending via SMTP. If you use only the Postmark REST API to send, no further action is required on your part.