[bitfolk] unwanted sendmail listener 63.141.225.90

Hi All, I just discovered an unwanted sendmail listener at 63.141.225.90 on my bitfolk vps machine by doing a % ps aux I still don't know how I was compromised. At any rate, it seems my sendmail config file is deficient. I've grepped through the /etc directory for the offensive address to no avail. When my email client opens, it tells me "Folder is open by another process, access is read-only". This concerns me, because there are no visible other processes. This is what caused me to look at 'ps aux', and discover the unwanted listener.  I believe this situation can be fixed, only I know not how. Any advice will be gratefully received. Cheers