Nov 04
Recipient addresses must be specified on the command line or via the -t option
Dedicated servers, Hosting Add commentsMany folks have been getting the error message sending email using php’s mail() function on Fedora, Red Hat Enterprise and Centos boxes, possible many others.
This error usually happens if you are using Postfix or Sendmail MTA. The error shows up in the maillog file as follows:
postfix/sendmail: fatal: Recipient addresses must be specified on the command line or via the -t option
You can fix this problem by editing sendmail_path value in php.ini file and uncommenting the following line (possible, making the changes to it as shown below)
sendmail_path = /usr/sbin/sendmail -t
Restart Apache and see if it works. It does for me 
November 6th, 2007 at 8:19 am
Some folks may benefit by using
sendmail_path = /usr/sbin/sendmail -t -i
as well. Feel free to test it out.
February 11th, 2008 at 11:10 pm
I was confused just by this error!!
Thank you for your describing.
I came to this page from Japan by Google.
March 27th, 2008 at 11:59 pm
thank you fixed my problem
sendmail_path = /opt/zimbra/postfix/sbin/sendmail -t -i