Form submission delay

We have our forms integrated in a wordpress site. We have  a number of forms and they're all lagging greatly between the time of submission and the time we see them in our gmail. Since last week it's been taking several hours to get to us. Even simple forms with no attachments or dropbox files are taking hours. 

Anyone else seeing this?

We are experiencing a delay issue on email notifications which have recipient emails like gmail or hotmail. This is already reported to our DevOps team and it should be resolved anytime soon. Please use your SMTP settings or your Gmail SMTP as the sender email for now to resolve the issue.

Update: Delayed email issue should be resolved now.

Thanks!