"Damn it, I didn't mean to hit 'Send'!"
"Hey, come back!"
There’s an old Roman fort east of the Nile in Egypt, out in the hinterlands, it doesn’t seem to have been a plum assignment, just a cruel necessity. A pile of such letters from home (and other stuff thrown out as rubbish) was excavated there. Given the length of time travel took, even in Roman times (the Romans basically eliminated piracy for centuries around the time they established their five major naval bases, including one in the Black Sea), I’d be surprised if some of the letters, maybe many or most, never got to their addressee, because they’d be reassigned, or even had died.