When comparing Rainlendar vs Microsoft Outlook, the Slant community recommends Microsoft Outlook for most people. In the question“What are the best calendar apps for Mac OS X?” Microsoft Outlook is ranked 9th while Rainlendar is ranked 13th. The most important reason people chose Microsoft Outlook is:
Microsoft Outlook comes with feature called "Clutter" to filter out incoming email based on the priority of the message set by user. User will be alerted when the high-priority message is incoming, whereas the low-priority message will be put in a separate folder.
Specs
Question Ranking
Pros
Pro Blends in with the desktop
This calendar stays out of your way, while remaining readily available to tell you what's coming up.
The Shadow skin make it look like a wallpaper calendar, but has the benefit of being interactive.
Pro Customizable
Take control of your calendar by scripting new functionality, take skins already created, or just disable all the fluff.
Rainlendar provides a platform to present your data in the way you desire.
Pro Integration
Your calendar data doesn't need to be stored with your computer. Data can be retrieved from Google, RTM, and even Outlook. (With the pro version removing annoying unregistered marks)
Pro Priority messages
Microsoft Outlook comes with feature called "Clutter" to filter out incoming email based on the priority of the message set by user. User will be alerted when the high-priority message is incoming, whereas the low-priority message will be put in a separate folder.
Pro Smart lookup
Smart lookup is a feature where the Bing search engine is bundled in the app to allow users to automatically search for relevant websites, information and images based on the word highlighted by users, without need to open external browsers. The results will be shown on the right pane of the window.
Pro Good built-in calendar
The calendar includes agenda, day, and three-day views.
Pro Integration with calendar and tasks
Quick conversion of a received email to a task with the deadline.
Pro Attach files from cloud
Microsoft Outlook allow users to directly attach an attachment directly from cloud services without need to download an entire file before attach to the intended e-mail.
Cons
Con Can be unstable
The calendar crashes from time to time when entering new data.
Con Rather buggy
Con No portable bundle available
Con Crashes frequently
The only issue with Outlook 2017 is that when the Mail folder increases in size, it sometimes crashes for no reason it, causing loss of data.
Con No aliases
Outlook does not support email aliases other then outlook aliases
Con The UI is outdated