Error when trying to send an email from vBulletin using SMTP server

[mportnov]

I tried to set up SMTP server settings for my forum but the diagnostics keep returning the same error all the time. I tried readyhosting.com based server and gmail server, but none of them work for me. I read all the related posts I found on this forum trying to fix the issue, but nothing helps.

Pertinent SMTP Settings
SMTP:	tls://smtp.zaliv.org:587
SMTP Username:	[email protected]

Help Results

The mailing function returned an error while trying to send the mail.

The following errors were outputted by PHP when attempting to send mail: Warning: fsockopen(): unable to connect to tcp://smtp.zaliv.org:587 (Permission denied) in [path]/includes/class_mail.php on line 741 Warning: Unable to connect to SMTP server in [path]/includes/class_mail.php on line 707

Thunderbird connects to the server using these settings without any issue.
Thanks in advance, I really don't know what to do with it.

[mportnov]

Resolved the issue myself. The problem was with selinux blocking outbound traffic.
I went to /etc/selinux, changed this line:
SELINUX=enforcing
to:
SELINUX=permissive

Then I restarted the server:
shutdown -r now

And voila! SMTP server becomes reachable.