Sendgrid emails

I've been using this app to send emails via Sendgrid for months now but recently my emails are showing as "queued" in the logs. I haven't made any changes except for upgrading my C-7 and I don't send more than 4 emails per day. Anyone experiencing similar problem?

What do the logs in SendGrid say? They have some detailed logs that show delivery failures, etc.

I as well have been using it for months. The last 2 days it takes up to 10 minutes sometimes and other times no email at all. Not sure either what is going on.