Last year, we launched the Just create Drafts feature, which allows you to have your mail merge campaign created as Gmail Drafts first, so you can spot check them for accuracy, and then click a link to send all of the Drafts.
We just enhanced the feature to work more efficiently. Before, often several of the Drafts would fail to send when you clicked the link, causing you to have to click the link a second time to get all the Drafts sent. You would have received an email informing you of this, that looked like:
This was due to a sometimes faulty Gmail API that would return an error to GMass rather than sending the Drafts. We’ve now worked around the Gmail API issues to make this feature much more convenient to use. Now, GMass will attempt to send all Drafts, and upon a failure, will attempt to send several more times.
Now, it should be rare that you have to click the link multiple times to send all the Drafts.