Why we have stopped receiving e-mail notifications for our Image Submission form?

This is now the third or fourth time this has happened recently, every other time ya'll resolved this very quickly for us, is it something we're doing wrong? Could we change something to avoid this? Thanks ahead of time!

I checked your form, your email was in bounce list and the reason is below:

I removed your email from our bounce list and your submissions should go through normally.

Please check this thread on how to prevent similar issues.

We're sorry for this inconvenience.

Thank you!