For one thing, the mail strike is only a rotating strike. This means that it hits one city one day, then another another day, and so on and so forth, so at worst it's just a temporary nuisance.
For a second thing, if the union would be so stupid as to go on a full strike, the government would step in and legislate them back to work. So that would be the end of that.
For a third thing, it doesn't ,matter, because we have UPS, FedEx and a whole range of delivery options that we use as well, depending on the circumstances.
Last but not least, the good old USPS is only one hour away.
So don't worry. (Be Happy!) Everything is just fine.