Mail programs and attachment


I like Comodo FW but I see next problem. It is very strange behaviour - I can send text mails but if I try send photo or mp3 I cant do that. Smtp problem. I tried Opera mail, Thunderbird and The Bat! Result is always the same (:AGY) I use default settings of Comodo, only Outlook is blocked because I dont use it.
I have no idea why attachment is blocked :THNK
Any idea?