I am getting familiar with Amazons EC2. I installed a LAMP setup but when I try to send emails through the mail() function that I have in my pages it does not work. I checked and sendmail is running and is on the phpinfo page.
I have tried changing the php.ini sendmail_from and it does nothing. SMTP port is open on the firewall... im freakin lost..
This won't directly solve your issue (edit: I mean the error message you have now edited out), but Amazon EC2 instances have a really spotty mail reputation. You're probably going to have deliverability issues.
Thankfully Amazon created the Simple Email Service to go along with EC2, with a free level of service for EC2 customers. The API is pretty simple and there are transport adapters for many excellent PHP mailing libraries, like SwiftMailer (transport).
Please install sendmail extension, I solved this issue just by installing sendmail in my instance.
Just type: sudo apt-get install sendmail in your terminal.
That worked for me
来源：https://stackoverflow.com/questions/5292170/ec2-fresh-php-install-mail-not-working