Fetchmail VS IMAPSize

The Fetchmail Project

Versatile Protocol Support
Fetchmail supports a wide range of email protocols, including POP3, IMAP, ETRN, and ODMR, allowing it to retrieve emails from a variety of mail servers.
Remote Mail Retrieval
It allows users to download emails from remote mail servers to their local machines, making it easier to consolidate emails from multiple accounts into one place.
Flexible Delivery
Fetchmail can deliver messages to the local SMTP server, making it compatible with various local email delivery setups and configurations.
Open Source
As an open-source project, Fetchmail is free to use and can be modified according to the user's requirements, making it a flexible solution for diverse email retrieval needs.
Configurable
Users can customize Fetchmail's operation with a wide array of configuration options to suit their specific email retrieval and processing needs.

Complex Configuration
The configuration of Fetchmail can be quite complex, especially for users who are not familiar with command-line tools and server setups.
Security Risks
As with any tool that handles email retrieval, there are potential security risks if Fetchmail is not configured correctly, such as vulnerabilities to man-in-the-middle attacks when using insecure protocols.
Limited Functionality
Fetchmail primarily focuses on fetching and forwarding emails and does not include advanced email management features that may be found in more comprehensive email client software.
Limited Error Reporting
Some users may find that Fetchmail's error messages and logging do not provide enough detailed information to diagnose issues effectively.
Maintainability
For users who require regular updates and support, Fetchmail may not meet expectations as its development activity can be sporadic, potentially lacking regular maintenance updates.