Not only that we should all send them emails telling them they will no longer get our business and encourage our friends to do the same.
I, like Hans, don't know if this will do any good or not ...... but there are many, many (millions) of us gun owners. And unlike "Dick's" and "C T D", who have many other products to support them, UPS has only the shipping business (typically) to carry them.
If we all send emails saying basically the same thing, it might cause a re-think from UPS. With enough numbers of emails they may realize their business might actually suffer from no reason other than them at corporate becoming political, and that their shipping has nothing to do with the 'original sin' of purchasing a firearm anyway, and that them refusing to ship firearms, etc, means little to us because there are other means of shipping available to all of us, they might reconsider. And we need to remember this decision was made at the corporate level rather than the majority of rank and file employees, many whom are also gun owners, not to mention the stock holders, things might look a little different to Corp.
It certainly can't hurt and there's the off chance that some or several/many smaller companies other than UPS that can't stand that kind of heat will hear about it and won't get into the fight to begin with.
I fully intend to email/write/phone anyone in a leadership position at UPS as many times as is practical. We must remain professional and respectful, but we must make it clear of our intention. jj