Today I’m excited to share with you today’s launch of my new product,, an email campaign testing and rendering service. is a free service that assesses the spammyness of your campaign, checks for broken links, makes sure you’re not on any blacklists, and shows you what your email looks like in popular email clients like Yahoo! Mail, Gmail, Outlook, and Thunderbird.

All you have to do is send your campaign to and you’ll get a report sent right back to you.

It doesn’t matter whether you’re using GMass or any other email marketing service like MailChimp or Constant Contact…it works with all of them since you only need to send your email to to use the service. is being launched on Product Hunt today, so if you’re a fan, please join the conversation there now! is being launched on Product Hunt today!

Note: Eventually, I’ll add a button to the GMass interface that sends your email to, but for now, you can use the “Send Test Email” button in GMass to send to

Exciting news! We’ve re-engineered how GMass connects to Gmail to make it so that you can send mail merge campaigns that are a whopping 35 MegaBytes in size.

If you’ve previously encountered the “Your email exceeds the GMass size limit” or the cryptic “An Error occurred, but the error response could not be deserialized” error when sending big emails, that’s all in the past.

What can you attach to a 35 MB email campaign? These are just estimates but..

  • 10 MP3 songs
  • 20 high res images
  • 30 optimized PDF files

If you can dream it, you can mail merge it. Note that attachments and images can almost double in size when encoded into the format necessary for email transmission (MIME), so allowing 35 MB actually means a max of about 17-18 MB of attached files and images. Still though, this is more than double the previous size limitation.

Keep in mind that while I’ve made it possible to send huge 35 MB email campaigns in Gmail, your recipients may not feel the same excitement, especially those people reading your email on smartphones and paying for mobile data plans. So use this newfound power wisely!

Using a combination of Gmail, Google Sheets, and GMass, you can easily set up automated birthday emails to go out on people’s birthdays or any other specific date you like. In the Google Sheets spreadsheet containing your email addresses, you simply need a Date column that includes the date on which you’d like that particular email sent.


The basic steps to send automatic birthday emails in Gmail involve:

  1. Setting up a Google Sheets spreadsheet containing email addresses and birthdays.
  2. Using GMass to connect to the spreadsheet with a specific filter criteria.
  3. Composing the campaign and setting it to repeat daily.

Set up your spreadsheet

Your spreadsheet can contain any number of columns to personalize your emails, but at a minimum, for this to work, it should include a column for the actual email address and the date. In this case, we’ll assume we’re sending emails to people on their birthdays. In addition to the Email and Birthday columns, we’ll also include the first name and last name so that we can send a properly personalized email to each person on his/her birthday.

A sample spreadsheet containing a list of people and their birthdays. Note that the birthdays can be in any valid date format and need not contain the year.

In what format should the date be? Your date column can contain dates with years or without years, and they can be in any recognizable U.S.-based date format. For the date of January 15, 1985 for example, the spreadsheet cell can contain “1/15/85”, “1/15/1985”, “01/15/85”, “January 15, 1985”. It should not contain, however, the European date format of “15/1/85”.

If you want to leave years off of the date, that’s fine too. “1/15” and “January 15” are acceptable date values also.

Set up the filter criteria in GMass

Click the GMass spreadsheet icon and choose the spreadsheet and worksheet that you just set up. Because we don’t want to send an email to everyone on the spreadsheet, we need to specify filter criteria so that emails only go out when today’s date matches the date in the Birthday column.

The filter criteria is based on the “Birthday” column in the spreadsheet. We want to match rows where the Birthday is equal to the current date, without regard to the year of the Birthday.

Once you’ve inputted the filter criteria, click the CONNECT TO SPREADSHEET button to continue.

Note: If it’s nobody’s birthday today, then the Gmail Compose window will launch with an alias address in the To field representing 0 addresses. That is normal. It just means that right now, 0 emails will be sent. Since you’re going to set up the campaign to repeat daily, it will check to see if it’s anybody’s birthday on each day the campaign runs.

Set up the actual mail merge

A Compose window in Gmail should have launched where you can enter the Subject and the Message for the birthday email. Here I’ve personalized the Subject with the recipient’s first name, and I’m personalizing the Message with the first name.

Don’t be alarmed by the alias address representing 0 recipients. That’s just because it’s not anyone’s birthday today!

Now, in order to get this email to send every day to just the people whose birthday it is on that given day, you must check the Repeat daily checkbox.

The key setting of an automated birthday email campaign is to set it to “Repeat daily to new Sheets addresses”. That will cause GMass to query the spreadsheet daily to see what email addresses match the filter criteria. Without this setting, the email will send today to anybody whose birthday is today, and then will stop.

That will tell GMass to:

  1. Query the spreadsheet daily for rows where the current date is equal to the Birthday date.
  2. Send an email to just those people.

You can keep adding rows to your spreadsheet, even after the birthday campaign has started

You can add more rows to your spreadsheet anytime you wish, and GMass will automatically pick up the new email addresses and dates. You don’t need to edit your GMass campaign. Just add the new data to the spreadsheet and GMass will detect them and send the emails accordingly on the daily schedule you’ve already set.

Best Practices for Birthday Emails

What makes a good vs bad birthday email campaign? Check out The Pros & Cons of Birthday Emails, written by the folks at AWeber.

Get more replies with auto follow-up emails

Using this birthday email technique paired with automatic follow-up emails will get you even more responses to your birthday emails. In this example, setting just a Stage 1 auto follow-up will increase reply rates.

Adding auto follow-ups to birthday emails is a powerful way to maximize your response rate.

That’s all!

You can use this feature to send automated birthday emails or automated emails based on any date. For example, if you have a spreadsheet of orders your company has received, and one of the columns is the buyer’s email address, and the other is the buyer’s order ship date, you can have an email sent out automatically on the day that a buyer’s product ships, to let them know to expect their package in the mail soon.

Is your email list not in Google Sheets?

GMass integrates extensively with Google Sheets to make features like sending automatic birthday emails possible. What if you don’t use Google Sheets as the main warehouse for your email list data? Using one of the many Google Sheets integrations from Zapier, you can automatically sync data from almost any database system with Google Sheets.

Further Reading

You may be interested in an overview of how GMass sends mail merge campaigns with Google Sheets. You may also be interested in reading about setting up daily recurring campaigns using data in Google Sheets, which is what is necessary to send birthday and date-specific emails. And lastly, here’s a detailed guide to filtering rows in your spreadsheet for mail merges, in case you want to learn about techniques beyond just date filters in choosing which spreadsheet rows to send emails to.