Appear.in was acquired and they're consolidating services and infrastructure. Nothing we can do.
This is a perfect example of why we have made the changes we have. SmarterMail is a HUGE software product with millions of lines of code and integrations with dozens of companies (via API, protocols or included libraries). We are also very dependent on things not in our control such as: iOS, Android, MacOS, Samsung, OnePlus, antivirus providers, anti-malware providers, firewall companies and the list could go on.
It is impossible to keep old versions of our products which have significantly different code bases supporting not only old technologies but even more so the new technologies. This is why the software industry is transitioning into software as a service!
Hope this helps and I appreciate you bringing up the appear.in changes. It really is a perfect example of what we face on a daily basis. In most cases, we can avoid customers seeing these changes but clearly appear.in is a customer facing scenario. This is also why we transitioned to providing our own audio/video solution with SmarterMail -- we control it and we can make changes and updates to it that our customers want.