A program that does not fall into any other category.
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
F-Secure Anti-Virus can detect certain compressed/archive files that have a big compression ratio (for example 1 megabyte archive or compressed file that expands into tens of megabytes of data) as 'Mail Bomb'.
This does not mean that any infection was found in those files, it's just a warning.
If you have a file detected as Mail Bomb, please exclude it from scanning for both On-Access and On-Demand scanners of your F-Secure Anti-Virus.