I did notice for a few hours yesterday in the morning (BST) that PMs weren't appearing in my sent-mail folder, nor getting to their recipients, & same w/comment notifications -- though after several hours this all seemed to be ironed out (& I was in a training all day yesterday so not really having the time to file a support request) -- not sure if this was related? As I said, it seems to be ironed out now, but mentioning it in case it's useful data.