Firstly let me be very clear - I don't want this to turn into an "X is better than Y" and "No, Z kicks Y's butt" thread because it'll get closed quickly. I want to add some additional scanners to a MailScanner (www.mailscanner.info) install. They don't need to be deamonised or anything specific to a mail server, just the regular linux command line scanner is required. I'm already running clamd, and I suspect an additional 3 engines is the absolute maximum I could add before scanning starts to consume a few too many resources. As it's not realtime I don't care about anything other than these criteria: Scan Speed Detection Rate Reaction Speed i.e. time to release updates for example the recent UPS/Fedex trojans Price to Performance Ratio i.e. if you were to consider engine Y 5% better than engine Z but engine Y cost 10x the price I'd choose Z. These are the options: antivir avast avastd avg bitdefender clamav clamd clamavmodule command css drweb esets etrust f-prot f-prot-6 f-secure inoculan inoculate kaspersky mcafee nod32 norman panda rav sophos sophossavi symscanengine trend vba32 vexira Suggestions and reasons appreciate - as I said I don't want to get into X vs. Y or anything against the forum AUP I would just like to know which you would choose and in which order and any specific reasons.