Apple has released a documentation for developers, regarding a new requirement that will be in effect when macOS 10.14.5 is launched. This documentation states that developers must prepare their software for notarization.
It is important to note that notarization is not App Review.
Apple’s notary service is explained as an automated system that will scan the software in question for code-signing problems and malicious content. The process is said to be quick, and if there are no issues found, the notary service will then generate a ticket for the developers to include in their software.
At the same time, this ticket also gets published online, so Gatekeeper can find it. When you install the app, the presence of the ticket will tell Gatekeeper that this software was notarized by Apple. Users will receive descriptive information about the app, so they are aware that Apple has checked the software for malicious presence and that none was found.
The notarization process is required only for non Mac App Store apps.
Developer IDs are provided by Apple to trusted non Mac App Store developers. These IDs are needed to allow Gatekeeper to install non Mac App Store applications on macOS without displaying warning pop-ups. Notarizing takes software security on the Mac App Store a step further.
Apple also recommends developers to notarize all of the software they’ve distributed, including older versions of it.