This came today from an investment outfit. I have no idea what it means--

"We apologize for being unable to household this particular mailing; because it contains account-specific material we were only able to combine accounts with identical registrations within the same letter."

What connection could this have with a household? Might they be using it as some kind of metaphor?

Just a guess -- if you have more than one account with these people (but through different branches or perhaps opened at different times, or different members of your household have separate accounts), you will get multiple mailings from them. They can't combine the info from all the accounts into a single letter going to your household. (This happens to me with my bank, because my savings and chequings accounts were opened through different branches.)

Dear slithy: perhaps "household" is their jargon for mailings to a group of previously known investors, in contrast to a mass mailing. But the second half of the sentence baffles me.

boronia has pretty much nailed it down... but what a horrible anthimeria!

(verbing of a noun)

The project I'm currently working on aims to be able to identify "households" for exactly the same purpose as in Slithy's original post. Except that no one, even here, would even consider using the term as a verb to describe the noun!

no one, even here, would even consider using the term as a verb to describe the noun!

...even in such unlikely phrases as a "housing officer" or a "homing pigeon", I guess ;)