We've had similar variabilities in delivery/arrival dates...Sometimes the
agency says "no problem".

Sometimes it is a problem.  We had one proposal get signed off and copied so
late that the PI had to board a plan to DC that afternoon (cash, no luggage,
a very small carry-on - the proposal), hightailed it to Rockville, MD in a
made-for-TV-movie high speed taxi ride and literally rush it in to the
receiving area.  (The proposal ended up getting funded, by the way).
Needless to say, these days that won't work since NIH et al no longer accept
personal deliveries of applications.  Plus, one can imagine the security
checks and delays on someone boarding a plan at the last minute paying with
a credit card, no luggage, no coat or jacket, no carryon bag except this one
FedEx parcel....hmmmmn.

(As a footnote, the next day the program officer later said that if it had
arrived early the next morning instead of 4:55 PM the previous day, that
would have been OK.   Maybe, but the PI wouldn't have been able to sleep.
In any case, all subsequent applications were ready to go days in
advance...lesson learned).

NSF tends to regard its deadlines as "target dates", and if proposals are in
a day or two later, they have no major problem.  Especially if you call the
program officer to let them know, and why.

NIH, on the other hand, tends to be pretty strict, and more-or-less stick to
published arrival dates as THE deadline.  In certain highly unusual
circumstances (devastating floods, tornadoes, acts of nature, etc.) they'll
publish or allow a variance for adjusted receipt dates.

For foundations, it depends upon the program officer.  Usually they are
flexible, but sometimes the deadlines are absolutely carved in stone (and
they point this out in print, but not in stone, alas).

Overall, the general rule is check with the program officer at that specific
agency and department beforehand .
BG

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