If you're using ESS and not EAV, add the senders to the Whitelist. Most likely some of the servers the email goes through are blacklisted due to a huge number of spam sent through them. If you're using EAV, it must be another application that adds it to the subject.
How can I know which servers are those? are those mine or from people I get emails ? Its not from everyone I receive this, but just from some people.
First of all, can you confirm or deny that you're using ESET Smart Security? I'm asking coz you've posted to the NOD32 Antivirus forum.