When comparing Microsoft Outlook vs Spark, the Slant community recommends Spark for most people. In the question“What are the best e-mail clients for macOS?” Spark is ranked 3rd while Microsoft Outlook is ranked 15th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
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 Fun to use
clean and smooth experience, very nice and i like it.
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 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 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.
Pro VBA macros
Pro Conditional formatting
Pro Cloud
can attach files and use cloud, very good.
Pro Custom quick swipe features
Pro Free
Pro Robust customization options
Pro Syncs across devices
Pro Unified inbox
Pro Free snooze options
Cons
Con It's from Microsoft
Con Rather buggy
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 Categorize email IMAP not good
Con Frustrating user experience
The "Clean Interface" approach means that normal and necessary user interface elements have been removed, such as certain scroll bars, and even the "replied to" indicator. This program becomes more frustrating with each new update.
Con No unique Inbox / global folders
Con No portable bundle available
Con No aliases
Outlook does not support email aliases other then outlook aliases
Con The UI is outdated
Con Only available for Windows
Con Horrible privacy policy
- Sends statistical data to several services known for bad privacy policies (Google, Facebook), also there's no way to opt out.
- Automatically creates an acount with the first address entered and subscribes you to their newsletter.
- Stores credentials for your email accounts on their servers.
- Stores your emails on their servers to push them to your devices.
- Server infrastructure seems to be located in the US.
Con Doesn't support many services
Many services such as Spam filters, Pocket, and other apps are not supported.
Con Doesn't show the counts of emails next to the folders
- On the Mac platform will show +999 for the folder that contains more than 1000 emails.
- On the iPhone, the platform will not show the counts next to the folder unless they are new emails.
