ModusGate is a mail server able to handle its own mail (with a web mail interface included) or relay on to another host. We relayed mail to our Microsoft Exchange service on the same server, and while this was easy to set up, some of it could have been streamlined, such as reallocating TCP ports to avoid conflict.
Mail filtering is in a hierarchy in which specific settings override parent options (for example, global settings are superseded by domain settings). This provides great flexibility and the ability to handle complex environments with minimum fuss. The system also offers a fully-fledged scripting language for really hands-on DIY filtering.
Overall, the web GUI is easy to use. Common functions are controlled by oversized toolbar buttons and menu options provide access to less common tasks.
Signature updates are easy to retrieve but there is no feedback until the update is installed or has failed, which leaves the admin in limbo if the connection is slow.
The software can perform a variety of logging to a SQL database, though most is disabled by default. The documentation is helpful here too, explaining how SQL queries can be constructed to extract and analyze the logs. We would like a tool to do it for us, but the reporting options are good.
The quarantine is simple but informative, including details about which rule triggered the block, which is important for tuning. Filtering was good. The product stopped a lot of spam with few false positives (the GUI made configuring around them simple). Throughput was acceptable, but complex rules lead to lengthy processing.