When comparing Mozilla Thunderbird vs Microsoft Outlook, the Slant community recommends Mozilla Thunderbird for most people. In the question“What are the best e-mail clients for Windows?” Mozilla Thunderbird is ranked 1st while Microsoft Outlook is ranked 3rd.
Ranked in these QuestionsQuestion Ranking
Pro Free (as in freedom and beer)
Pro Lightning Calendar and Address Book integration
Pro Good filtering system
Mozilla Thunderbird offers a flexible filtering system with the ability to set flags and read/unread, as well as sort/assign to new mail directories. There are also numerous plugins available to assist in the filtering.
Pro Consistent and involving a moderate learning curve
The app design of Mozilla Thunderbird has not changed significantly since its beginning, making its learning curve almost non-existent.
Pro Available on Linux, OS X and Windows
Pro Large assortment of plugins available
Mozilla Thunderbird offers a huge amount of extensions to expand the usability and options of the client.
Pro Very reliable
Version after version, Mozilla Thunderbird works as expected.
Pro Tabs for navigation
Pro Send large files easy
Install pCloud plugin for Thunderbird and your files (upto 20 GB free storage included) will be received as download links
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.
Con Terrible integration with macOS
Simple things - drag/dropping pictures doesn't work, for instance.
Con Development slowed to only focus on stability and security
Mozilla Thunderbird has slowed down its development of features to only focus resources on security and stability.
Con Subject lines can (temporarily) disappear from the list
This is sporadic behavior.
Con Serious bugs
Clicking on a subject line can bring up the wrong email.
Con Outdated interface
Thunderbird's interface is very outdated and unpleasant. It feels more like a Windows XP application than like a modern MacOS one.
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