[toaster] My email was from an error address?

[qmail]

I have installed a qmail server named my.com following The
Qmail-toaster.All seem to be right.OK.
    But I found recently some email from my server(my.com) have been
modified,the email address was an strange address example.com.
    Why? Can you help me?



Sorry,My first language was not English,so my english is very poor.