They did a lot of big projects at the end of the year, not a good situation. I am sure they are waiting for payment from the really big clients who also like to pay whenever they feel like it.
However, why send an email indicating payment was made when they could have instead that there is a delay? I don't see a problem with honesty. Sure people will be upset, but this payment issue is a well known reality.
I think this is why a number of companies (including some super big ones) still do check because you can't hide under ACH or maybe paypal. I don't often see checks mailed on the indicated date either, but as long as they come within a few weeks of the expected date I guess that is how it goes. But sending checks is not worth it because they are all clearing electronically via a picture. I am not sure when some of these big ones understand that money floating is not as viable (except for how they hold checks physically which is obviously happening).