Ok im trying to make popa3d and it spits me out this, and I dont understand it. I would greatly appriatiate if someone can please help me out! Thanks.

gcc -s version.o startup.o standalone.o virtual.o auth_passwd.o auth_shadow.o auth_pam.o pop_root.o pop_auth.o pop_trans.o protocol.o database.o mailbox.o misc.o md5/md5.o -lcrypt -o popa3d
auth_shadow.o(.text+0x0): In function `auth_userpass':
: multiple definition of `auth_userpass'
auth_passwd.o(.text+0x0): first defined here
/usr/bin/ld: Warning: size of symbol `auth_userpass' changed from 154 to 433 in auth_shadow.o
collect2: ld returned 1 exit status
make: *** [popa3d] Error 1

Hmm... I have no clue about the specific program you are talking about, but are you sure you need both auth_passwd.o and auth_shadow.o? From the errors you posted, it looks like parts of them might be redundant, so maybe you're only intended to use one or the other. If the file /etc/shadow exists on your system, try using auth_shadow.o, otherwise, try auth_passwd.o.

This is all just a guess, I have very little clue what I'm talking about here.