High recursion of MIME parts causes antivirus to crash.
vulners.com/securityvulns/securityvulns:doc:15327
vulners.com/securityvulns/securityvulns:doc:15328
vulners.com/securityvulns/securityvulns:doc:15329
vulners.com/securityvulns/securityvulns:doc:15352