Octopus Energy posted me a 321 A4 page electricity bill printed out on paper as a physical 5cm thick package (on their "Agile tariff" the rate changes every half hour, so there are 48 line items per day). I enquired as to why they'd done that?
Apparently they tried to email it first, but the 15 MB email exceeded my email server's size limit, so they posted a hard copy instead.
@tim been there, done that. Although in my case it was because their mail server was sending malformed mails which mine rejected. I pointed out that I could just download the bill from their website, but they said that legally they had to send one so it carried on for a year. I'm sure legally they don't need to send anything *that* detailed - a summary and a pointer to their website for more detail would surely be fine?