i am in problem

[Khounish Dasgupta <kshounish@xxxxxxxxx>]

can any body help me by telling the fact and solution
of my question a nd write me to kshounish@xxxxxxxxx 
i  am a faculty and i was configuring sendmail . well
by gods grace its well configured and i am sending
mail trhough pine and  getting mail through fethmail
also succesfull.
but getting two problems 

1) using pine i am getting succesfull but why not
through "mail username@domainname"

2)pleaase tell me another thing that for exmining
whetther the mail is going or not what i di was i just
wrote in pine and send it it went in my yahoo acount
with a header from : mymachinename@domainname
but when i said reply it send the packetg but couldnt
reeach o my amchine me  can u tell me the cuase and  
what to do  at that point
 thanks in advance but i am in tremendous need of this concept

__________________________________________________
Do You Yahoo!?
Get personalized email addresses from Yahoo! Mail - only $35 
a year!  http://personal.mail.yahoo.com/