Email sending not working on setup (PHP/WordPress)


I have WordPress installed on a Droplet with WP SMTP plugin(with Gmail setup configuration). It works when I send a test email via plugin page inside WordPress admin panel. Follow to that, I installed postfix to deliver emails. I have WordPress Contact Form (contact form 7) plugin installed which triggers email sending.

But, when I run this command, and check my inbox, I don’t receive any email.

echo "Test Email message body" | mail -s "Email test subject" <my-email-address>

When I checked my log file (tail -20 /var/log/mail.log), following is what I see there.

Jul 11 04:50:39 ch-graphql postfix/smtp[32233]: 54B4281672: to=<>,[]:25,
status=bounced (host[] said: 550-5.7.28 [       1]

Our system has detected an unusual rate of 550-5.7.28 unsolicited mail originating from your IP address. To protect our 550-5.7.28 users from spam, mail sent from your IP address has been blocked. 550-5.7.28 Please visit 550-5.7.28 to review our 550 5.7.28 Bulk Email Senders Guidelines. m134si5397108pfd.183 - gsmtp (in reply to end of DATA command))

What could be wrong here? Let me know if you need more information. Thank you in advance.


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Hello there,

It is recommended to use ports 465 or 587 instead of insecure ports like 25 and also to use an SMTP plugin as well.

I’ll also recommend using a third-party mail provider like SendGrid to send your emails. You can also check this tutorial on: Why You May Not Want To Run Your Own Mail Server

Hope that this helps!


It looks like that your IP address does not yet have a good mail reputation. What you could do is use Gmail SMTP for the time being to prevent your emails from being rejected.