Why your Gmail account becomes inaccessible when sending a big mail merge campaign

If you’ve ever been locked out of your Gmail account while sending a large mail merge campaign, you’re not alone, and don’t be alarmed. It’s normal Gmail behavior, and you’ll be able to use your account just as soon as sending is complete. During a large mail merge with Gmail, you might see this message telling you “the system encountered a problem” if you’re already in your account:

You may see this “Oops” message when trying to check your email while a big mail merge campaign is sending.

Or, if you’re trying to reload Gmail in the browser, you might see this “Temporary Error” message:

If you reload Gmail during a big mail merge, you might see this screen.

Why does this happen?

Gmail wasn’t originally meant for sending mail merge campaigns or email marketing campaigns. GMass has finagled Gmail to make it possible, but Gmail’s User Interface isn’t able to process all the network activity that takes place during a mass email send. Whenever you send an email in Gmail, your browser makes several requests to the Gmail server in order to update the User Interface on screen in front of you. When sending hundreds or thousands of individual emails, the User Interface can’t keep up with this network activity. Therefore, in order to protect itself from even more network activity, it withholds your access until sending of the email campaign is finished.