[nexus123]

For me, 70kb on average looks too much to me if I am basing on Gmail’s statistics. Each page of Gmail is 50 individual email threads (that is, not counting the number of replies).

I have a total of 12,592 pages and according to Gmail's usage report, 2GB belongs to Gmail and 1.47GB belongs to Google Drive and Photos. So 2GB/(5012592) is about 3KB per thread?

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&e...

Let alone the amount of attachments (some are a couple MB).

And Google said "Attachments sent and received in Gmail as well as your email messages use your storage.” [1]

[1]: https://www.google.com/settings/u/1/storage?hl=en

So this number Gmail is showing would be the compressed storage space taken on their side?