macOS
- macOS 10.13 through macOS 14
- Intel or M1/M2 processor that can run in 64-bit
- 8 GB of RAM
- 200 MB hard drive space for application files (excluding local message data)
- Postbox runs in 64-bit mode on macOS
Windows
- Windows 8 and higher
- Pentium 4 or newer processor that supports SSE2
- 8 GB of RAM
- 200 MB hard drive space for application files (excluding local message data)
- Postbox runs in 32-bit mode on 32-bit and 64-bit versions of Windows