From last two days we were running into an issue with the Postmark API based email attachments, specially when you have to use the remote file url for the attachment. Also we were not seeing any error logs for non-delivery of attachments. So Swati and I started with different approaches to solve the problem. I will be explaining here the approach where I directly used the Postmark API key and tried to send an attachment with email using CURL command. Whereas Swati will soon add here post about sending email with attachment using postmark-rails gem and what was causing issue