Google temporarily disables Gmail accounts if there's been a lack of activity within your inbox. At times, Google will mention that the email was disabled due to suspicious activity on your email account.
This can happen occasionally if Interseller is running, but you're not interacting with your Google account as often as you used to (i.e. actively using your Gmail account to send or receive emails within the Gmail app).
Google does this to ensure that your account hasn't been hacked and that you're not a bot. This is similar to other websites using reCAPTCHA to confirm you're a human and not a bot.
To resolve this, simply login to your Gmail account to reactivate it and you should be good to go!
After you reactivated your account, we recommend increasing your time between emails if you aren't sending non-Interseller emails on a regular basis.