it's will help you for your blesta email be not assimillated as spam or a spammer simulate being you, if you have some DNS TXT records like:
1/ A TXT DNS RECORD to definite allowed sender, so you will list your server IP(s):"v=spf1 ip4:85.214.93.191 ip4:85.214.149.150 -all"
2/ A TXT DNS RECORD FOR DKIM
Other, regarding your permission level on the pipe file, there should not have relation as said Paul, but your mail box (mail server) is on the same server as your Blesta install? If not it's explain you needed 777 level, but using piping is only when all is on same server.
if you are well on same sever, if you needed 777 for that work, it's could mean you user/group didn't own any right on the piping file and that really bad to solve it by giving full right to anybody