There was an issue, but it seems to be resolved.

This is what they said:

Dec 14, 2023, 1:41 PM CST

We’re currently working through a service disruption and appreciate your report - it will help us better understand the scope and impact of the incident. Our team is actively working to resolve this issue, and we will provide more information as our investigation continues. Apologies for the inconvenience!

And then this:

Dec 14, 2023, 1:53 PM CST

After restarting affected services, latency has dropped and incoming and outbound email in Sell is processing as expected. We will extend our monitoring through to tomorrow to allow the team to investigate further and ensure complete recovery.