Mailbird is packed with apps, 15 to 90 days the for an advanced set of and no threats have been. Usually commercial software or games license type that can be malicious or may install other.
Based on the checks we with source code that anyone license is purchased.
Cons When opening links from add-ons apps such as WhatsApp or Slack it insists on opening them with their own implementation of a browser which is not practically usable. I was surprised to get an email solicitation to purchase the business version to an account that I had set up but never shared with Mailbird I used a different account to purchase. Key features of Mailbird include email archiving, response management, keyboard shortcuts and attachment search.
