Thunderbird from Mozilla is a powerful alternative to Microsoft Outlook. It has all the features you would need in a desktop email client and it cost nothing,
General Navigation
| Action | Windows/Linux | macOS |
| Open Address Book | Ctrl + Shift + B | Cmd + Shift + B |
| Get New Messages | Ctrl + T | Cmd + T |
| Open Add-ons | Ctrl + Shift + A | Cmd + Shift + A |
| Go to Mail | Ctrl + 1 | Cmd + 1 |
| Go to Address Book | Ctrl + 2 | Cmd + 2 |
| Go to Calendar | Ctrl + 3 | Cmd + 3 |
| Switch Tabs | Ctrl + Tab | Cmd + } |
| Close Tab | Ctrl + W | Cmd + W |
Reading Mail
| Action | Windows/Linux | macOS |
| Next Message | N | N |
| Previous Message | P | P |
| Next Unread Message | Ctrl + ] | Cmd + ] |
| Previous Unread Message | Ctrl + [ | Cmd + [ |
| Mark as Read | M | M |
| Mark as Unread | Shift + M | Shift + M |
| Toggle Read/Unread | K | K |
| Delete Message | Delete | Cmd + Delete |
| Archive | A | A |
| Open Message in New Tab | Enter | Return |
| Reply | Ctrl + R | Cmd + R |
| Reply All | Ctrl + Shift + R | Cmd + Shift + R |
| Forward | Ctrl + L | Cmd + L |
Composing Mail
| Action | Windows/Linux | macOS |
| New Message | Ctrl + N | Cmd + N |
| Send Message | Ctrl + Enter | Cmd + Enter |
| Save as Draft | Ctrl + S | Cmd + S |
| Insert Link | Ctrl + K | Cmd + K |
| Insert Attachment | Ctrl + Shift + A | Cmd + Shift + A |
| Check Spelling | Ctrl + Shift + P | Cmd + Shift + P |
Folders and Messages
| Action | Windows/Linux | macOS |
| Move to Folder | Ctrl + Shift + M | Cmd + Shift + M |
| Tag Message | T | T |
| Add Star | S | S |
| Open Message Source | Ctrl + U | Cmd + U |
| View Headers | Ctrl + H | Cmd + H |
| Quick Filter Bar | Ctrl + Shift + K | Cmd + Shift + K |
Search and Filters
| Action | Windows/Linux | macOS |
| Global Search | / | / |
| Find in Message | Ctrl + F | Cmd + F |
| Advanced Search | Ctrl + Shift + F | Cmd + Shift + F |
Message Threads
| Action | Windows/Linux | macOS |
| Expand Thread | Right Arrow | Right Arrow |
| Collapse Thread | Left Arrow | Left Arrow |
| Expand All Threads | * then [ | * then [ |
| Collapse All Threads | * then ] | * then ] |
Miscellaneous
| Action | Windows/Linux | macOS |
| Open Developer Tools | Ctrl + Shift + J | Cmd + Shift + J |
| Preferences / Settings | Ctrl + , | Cmd + , |
| Exit Thunderbird | Ctrl + Q | Cmd + Q |
I hope these shortcuts make you more efferent at using Thunderbird. You can download it at https://www.thunderbird.net/en-US/.
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