What is it?
ossmtp.dll is a dynamic link library used by software to send and receive email

Is there a Virus Risk?
unfortunately, there is a mass mailing worm called w32.blackmal.c@mm that is also associated with the ossmtp.dll file!

What does the virus do?
W32.Blackmal.C@mm is a mass-mailing worm that lowers security settings by deleting files associated with security applications. It sends a copy of itself to all email addresses gathered from the Outlook address book, Yahoo Messenger address book, and Yahoo Pager address book.

More info and Removal Instructions
@symantec