Significant lag in Marketo support/admin emails

We're noticing significant delays (over an hour) in when an email is sent, to when it is received from Marketo.  This is affecting Marketo Support replies, password resets for our users and authentication code sends (for when Marketo thinks you're using a new device).  The latter happened to me today and it took me about three hours before I was able to finally login to Marketo.  Are others experiencing this?  Just wanted to make sure before I open a ticket with support.

FYI - community notifications are not affected by this.