We have a client that can't receive emails from a dedicated server using PHP mail because when their SPAM server does an MX record lookup for the IP it can't find one (so it bounces the email).
This is because the mail exchange is on a different server completely. The client said that they have an IP address that bypasses the SPAM blocker.
So I'm wondering if PHP mail can send an email to a specific IP?
Does your server not qualify as a mail sender by their spam filter? Because I'm guessing that they can receive mail from other people.
So I think you need to look at the setup of your server so it complies with their qualifications (like a reversible name for example, or whatever other rules they require from an email sender)
Because with PHP (and other languages) you just send the email, there are tools that send an email through another server that is qualified to send emails, but usually you use the server itself.
For example, you can use the Zend Mail library to send through another SMTP server.
The answer is yes. However, how the mail() call in PHP actually sends the mail is totally dependent on how your system is set up, so any problems you're having sending mail won't be resolved in your PHP code, they'll be in your mail set up.
Generally, you should be able to address a piece of email to "[email protected]" and have it arrive successfully.
There's a good article about some of your mailer settings here.