If an email sent from php mail() function returns, where is it located in linux?

Question

I have a page which sends and email to a specific user@domain.com via php mail() function.

But, the destination domain domain.com was not properly configured on DNS and none emails were received.

Is there any way to grab all those unsent emails?

Is there a location where unsent emails stay?

I am using Cpanel, but I have root access on the machine, also.

Answer 1

如果它正在运行postfix，请尝试查看mailq和postcat命令。