Cannot receive or send emails on my company mails

Question

I have this issue, I am not able to send or receive emails when I send them for example from: [e-mail] to [e-mail] if I send an email to external mail service such as gmail, yahoo, hotmail everything is delivered as should and also I can receive emails from external services perfectly fine. I am using php mail to send, also I am using VPS with CentOS and ISPconfig ( no Cpanel ). Is there something I can do to fix this?

Answer 1

You can't get an 100% reliable answer from outsiders on a website – you need to have someone actually check the company's mail server log files, where the rejection reasons will be documented.

That said, it's very likely that your company's mail service is configured to require that all messages "from" example.com must arrive through the company's own SMTP message submission servers – everything else is rejected as spoofed. This is a common tactic for blocking phishing messages and spam in general.

(In addition to that, the domain might even be configured to make other services reject your messages as spoofed using SPF.)

So you should probably find out what SMTP server the company's mail admins want you to use, and either configure it as a "relay host" in your server's Postfix/Exim/Sendmail configuration, or change your website to use PHPMailer instead of mail().