Lisa’s App of the Week – Email Optimization Tools



This app of the week features two crucial (and free!) email optimization tools we use to test the deliverability of our emails: MX Toolbox and Google Postmaster.

By Lisa Heay, Director of Business Operations at Heinz Marketing

For this week’s App of the Week post, I wanted to highlight two additional free apps that have helped us along on our email optimization journey. I’ve already covered one email optimization workhorse in a previous App of the Week post,, but there are a few more, MX Toolbox and Google Postmaster, that should make up any Marketing Operations professional’s arsenal.

MX Toolbox

MX Toolbox

MX Toolbox provides network diagnostic and lookup tools, enabling professionals to monitor, analyze, and optimize their email delivery, and diagnose and resolve a wide range of email and network infrastructure issues.

Users can perform tests to check the health of their email servers, verify email delivery, and troubleshoot any problems that may arise. The platform conducts checks on various parameters including blacklist status, SMTP connectivity, and message header analysis to provide a comprehensive overview of email system performance.

MX Toolbox also offers DNS-related tools and services. Users can analyze DNS records, perform DNS lookups, and troubleshoot DNS-related issues, ensuring proper configuration and functioning of the DNS infrastructure, which is crucial for email delivery and overall network stability.

For us, we use the free tools and regularly check to see if is listed on any blacklists, and ensure our DMARC is set up correctly. This tool was crucial in diagnosing an email sender issue which ultimately led to a dive in engagement rates.

dmarc check

MX Toolbox does have some paid features – and you can learn more about their packages here.

Google Postmaster

google postmaster

Google Postmaster is a service provided by Google to help email senders monitor and optimize their email delivery on Gmail—ensuring that legitimate emails reach recipients’ inboxes effectively.

This tool provides senders with detailed reports on metrics that help senders evaluate the effectiveness of their email campaigns and identify potential issues that may negatively impact deliverability.

In addition to inbox placement and domain and IP reputation, Google Postmaster will highlight the following for senders:

Delivery errors – allowing senders to pinpoint specific problems that may occur during the email transmission process. By analyzing bounce codes and error messages, senders can troubleshoot and rectify issues such as invalid email addresses or configuration errors.

Spam complaints received for a sender’s emails – enabling senders to identify potential content or sending practices that may trigger spam filters, allowing them to adjust their email content and sending strategies to minimize the chances of being marked as spam.

Email authentication protocols – provides data on the implementation and effectiveness of authentication mechanisms like SPF, DKIM, and DMARC. This helps senders ensure that their emails are properly authenticated, reducing the likelihood of their messages being flagged as spam or being spoofed.

All of your email recipients won’t use a Google platform for their mail, but we’ve found that if we’re getting good marks through Gmail, Outlook and other platforms perform similarly.

To wrap up

You may notice that these tools (and others, like Mail-Tester, which I’ve covered in another App of the Week post) check some of the same things. It’s true. But they are all still worth your time, because for us, one tool showed our DMARC as passing and another flagged an issue. Together these tools work together to show a pretty good, comprehensive view of email deliverability to ensure your messages are being seen.