I want to send mail with an attachment. Attachment size is 13.5 MB.

When I send an email with Attachments it is OK.

When I send the same mail with the footnote I have an error:
Exceeded the size limit
The size of this message is: 32 MB
The limit set by the administrator are: 25,2MB

Why add a footer to email increases its size more than doubled.
Footnote is composed of text and graphics with a size of about 100 kB.
I use GW2014 client for Windows.