VERY DANGEROUS.
The big credit card issuers like to impose time of day restrictions on payments. They even like to futz around with time zones, correct addresses, and whether stuff is paper-clipped or stapled.
NEVER try to cut it very close to the due date and time, or you run the risk of getting very severely burned.
I've only encountered one problem with B of A. That involved an electronic payment to a utility company that was not credited. I entered a complaint via their online interface, and the B of A rep got it straightened out within a day (the utility company had screwed up).