Yesterday afternoon, Copernica disabled file downloads upon the discovery of a security risk by one of our users. The reporting user was able to download random files by manually altering URLs. To prevent abuse, all file downloads were disabled completely on the spot.
Using the Sender Domain functionality of Copernica ensures that the DKIM, SPF and DMARC techniques are rolled out correctly. Moreover, your sending reputation can really benefit from the fact that the envelope, click tracking and from domain are 'aligned'.
Because of the positive impact that the use of Sender Domains has on the deliverability of our customers, we will make it mandatory from the 1th of November 2017. This means that mails with a from-domain that is not a validated Sender Domain, will be blocked automatically.
Thus, please make sure that all your domains are configured correctly. More information can be found in the documentation.