Post SMTP Mailer/Email Log

Actieve installaties: 300.000+

Buy product
Category: Tag:


Looking for Office 365 API delivery?

Check this extensions page, it will update with more extensions so don’t forget to follow:

The Only SMTP plugin with chrome Notifications

Get notified if your emails are failing inside your Chrome browser. Download here

WordPress Mail SMTP Plugin

Post SMTP is a next-generation WP Mail SMTP plugin, that assists in the delivery of email generated by your WordPress site. Post SMTP is the first and only plugin to support the latest security standards. With OAuth 2.0, there is no need to store your email passsword in the WordPress database where it might be found.

The Connectivity Test and intelligent Setup Wizard scan your SMTP server to detect firewall blocks and eliminate configuration mistakes. The built-in Email Log is an invaluable resource for diagnosing problems with emails. Even hosts that block the standard SMTP ports, like GoDaddy or Bluehost, can’t stop your email as Post SMTP can deliver via HTTPS if it can’t use SMTP.

Post SMTP is not another WP Mail SMTP clone like WP Bank or Easy SMTP. It replaces the default WordPress SMTP library, PHPMailer, with the heavy-duty Zend_Mail. Never lose an email to PHP mail() again.

The Most Fast And Easy

See how fast and easy to setup Post SMTP with Google/Gsuite or any SMTP service.

Standard Features

  • Easy-to-use, powerful Setup Wizard for perfect configuration
  • Commercial-grade Connectivity Tester to diagnose server issues
  • Log and resend all emails; see the exact cause of failed emails
  • Supports International alphabets, HTML Mail and MultiPart/Alternative
  • Supports forced recipients (cc, bcc, to) and custom email headers
  • SASL Support: Plain/Login/CRAM-MD5/XOAUTH2 authentication
  • Security Support: SMTPS and STARTTLS (SSL/TLS)
  • Copy configuration to other instances of Post

OAuth 2.0 Features

  • Supports the proprietary OAuth 2.0 implementations of Gmail, Hotmail and Yahoo
  • Fire-and-forget delivery continues even if your password changes
  • Gmail: By combining OAuth2 and the Gmail API, Post can deliver where other plugins can not

API (HTTPS) Email Support

  • Gmail API for sending Gmail and Google Apps email (requires a Google account)
    Often bloggers and small business owners don’t want to use third-party SMTP services. Well you can use your Gmail or G Suite account for SMTP emails.
    Check the guide I wrote

  • Mandrill API for sending any email (requires a Mandrill account)
    Mandrill is an email infrastructure service offered as an add-on for MailChimp that you can use to send personalized, one-to-one e-commerce emails, or automated transactional emails.

  • Mailgun API for sending any email (requires a Mailgun account)
    Mailgun SMTP is a popular SMTP service provider that allows you to send large quantities of emails. They allow you to send your first 10,000 emails for free every month.

  • SendGrid API for sending any email (requires a SendGrid account and PHP 5.3)
    SendGrid has a free SMTP plan that you can use to send up to 100 emails per day. With our native SendGrid SMTP integration, you can easily and securely set up SendGrid SMTP on your WordPress site.

Post SMTP needs translators! If you are a non-English speaker, please get involved!

Compatibile With..


  • WordPress 3.9 and PHP 5.6 with SPL and iconv
  • Memory: 750KiB per process at idle
  • Reliable mail delivery with custom email domains requires an SPF record
  • Reliable SMTP delivery requires credentials with an email service provider
  • OAuth 2.0 features require a Gmail, Hotmail or Yahoo mail OAuth 2.0 credentials

Looking for Google Analytics plugin?

If you used Google Analytics Dashboard For WP and you really hate the latest updates, I have forked the original plugin here:


Post SMTP (aka Postman SMTP) plugin was originally created by Jason Hendriks.

Grant OAuth permission error messages

Please note that the Client ID and Client Secret fields are NOT for your username and password. They are for OAuth Credentials only.

Error authenticating with this Client ID. [Error executing wp_remote_post: The user has blocked requests via HTTP.]

Your WordPress site is configured with WP_HTTP_BLOCK_EXTERNAL to prevent outbound connections. Add a whitelist rule to wp-config.php:

define(‘WP_ACCESSIBLE_HOSTS’, ‘,,’);

Error authenticating with this Client ID. [Error executing wp_remote_post: Failed to connect to xxxx]

There is a firewall on port 443 between you and the OAuth2 server. Open up the port for outbound connections.

Error: redirect_uri_mismatch

  • You did not enter the Redirect URI correctly, watch the instructional video
  • You used an IP address instead of a domain name (not allowed)

Error: invalid_client … no support email

You’ve forgotten to choose an email address in the consent screen.

SMTP Error Messages

Communication Error [334] – make sure the Envelope From Email is the same account used to create the Client ID.

  • This is almost always caused by being logged in to Google/Microsoft/Yahoo with a different user than the one Post is configured to send mail with. Logout and try again with the correct user
  • Login to Webmail and see if there is an “Unusual Activity” warning waiting for your attention

Could not open socket

  • Your host may have installed a firewall between you and the server. Ask them to open the ports.
  • Your may have tried to (incorrectly) use SSL over port 587. Check your encryption and port settings.

Operation Timed out

  • Your host may have poor connectivity to the mail server. Try doubling the Read Timeout.
  • Your host may have installed a firewall (DROP packets) between you and the server. Ask them to open the ports.
  • Your may have tried to (incorrectly) use TLS over port 465. Check your encryption and port settings.

Connection refused

Your host has likely installed a firewall (REJECT packets) between you and the server. Ask them to open the ports.

503 Bad sequence of commands

You configured TLS security when you should have selected no security.

XOAUTH2 authentication mechanism not supported

You may be on a Virtual Private Server that is playing havoc with your communications. Jump ship.

Mail ends up in the Spam folder

To avoid being flagged as spam, you need to prove your email isn’t forged. On a custom domain, its up to YOU to set that up:

  • Ensure you are using the correct SMTP server with authentication – the correct SMTP server is the one defined by your email service’s SPF record
  • If you use a custom domain name for email, add an SPF record to your DNS zone file. The SPF is specific to your email provider, for example Google
  • If you use a custom domain name for email, add a DKIM record to your DNS zone file and upload your Domain Key (a digital signature) to, for example Google

Main Menu