We'll be carrying on as normal, but monitoring the situation day by day - In our contact with the buyer, we do mention the postal strikes and possible delays through strike action and backlogs. So far this year we've had no problems.
With the strike action a few years ago, we more or less did the same thing, monitored and kept the buyer informed - and to be fair to all our buyers, we didn't receive any complaint from them re the time frame for delivery so they must have accepted and understood that it was something that we could not control.
With regard to purchases we were making at the time, some sellers gave us the choice of whether we wanted to wait until the strike was over before posting or not, and either way, we could not blame the seller for something that was beyond their control.