mutt没有这样的文件或目录

I am getting Can't stat filename No such file or directory when using mutt.

The csv file creates fine, my php mutt code is :

exec("export EMAIL=from_email && /bin/echo 'message' | /usr/bin/mutt -s 'subject' -a '$filename' -- 'email1@test.com email2@test.com'");    

The files are created in the tmp directory. I tried putting the files in another directory but got can't attach file permission denied.

I am using version 1.5.21.

Also are multiple email addresses separated by a space?