Update on 3/22/16: This feature has been enhanced. Bounces are now detected automatically and bounced addresses are suppressed in future email campaigns. This is part of the new Automatic Reply Management feature.
I just deployed a hack that lets you pull bounces from your Gmail account so that future GMass mail merge campaigns skip sending to those bounced addresses. If you already have a history of sending mail merge campaigns through your Gmail account with GMass, you’ve likely accumulated some bounce-backs. You already get ridiculously high email delivery rates when using GMass, but avoiding repeatedly sending to bounced addresses will optimize your email delivery even further.
This is a hack, and in time we will release a better bounce handling mechanism. For now though, here’s how to pull your bounce list and prevent GMass from sending to past bounces:
1. Use the Gmail search tool to search for “from:firstname.lastname@example.org”, and then search. This will show all of the bounce notifications you’ve received.
2. Next, click the GMass “Build Email List” button. This process could take a few minutes to complete if you have a lot of bounces in your Gmail account.
3. After it’s done, a new message will launch with all of your bounced addressed in the To field. Simply discard this message by hitting the Trash button in the lower right corner. GMass has now captured all of your bounced addresses and added them to our internal database. Now, if you attempt to send to any of these bounced addresses, GMass will skip over them.
In the future, we will automate the process of plucking bounced addresses from your account and adding them to our database, so that you don’t have to go through this manual process. Stay tuned for that.