One minor problem with sending BCC copies is that even the original "Sent" mail may not show to whom BCC copies were sent. The BCC addresses, at least in my email program, are deleted as soon as it leaves the "Out" box and moves to "Sent" mail. Other programs may to better(?)

If you have reason(s) to archive records of email correspondence, any significant senders/recipients should be as open TO:, FROM:, CC: persons that you'll be able to blameidentify later.

Of course, if you use html mail, you can't archive them anyway; so this minor distinction is of no concern.

For "public companies" a set of new SEC rules¹ makes it mandatory that some offices keep traceable records of all internal and external communications². I have yet to see any of the mavens who're wringing their hands over the complexities of complicance smart enough to comment on the possiblity of "untraceable" correspondence via BCC distributions.

¹ See "Sarbanes-Oxley Act 2002" for details.

² The principal "complexity" comes from the requirement that they have to be able to FIND and provide to the SEC "anything the SEC asks them for." - Are we all laughing now?

John