An email of that scale I often run by my manager anyway, simply because he's better than I am at writing things in a politically savvy fashion.

This is also better than Outlook's solution, which is simply "you can't send to that mailing list at all".

Where I work the really big lists are all moderated, with only 3-5 people allowed to post to the list. If you need to post something there, you mail one of the moderators the text you want sent on the list, together with an explanation what it is about and why you can't target a smaller number of recipients.

Email got a lot more boring since this was introduced.

That sounds like the corporate version of the Soviet Union. Oh, you want to have a meeting with more than five people?

Please fill out the reason for that on this form and we'll get back to you.