You can do it, but keep in mind that if your email occupies more than 100 kB, the system will account an email for each additional block of 100 kB. If for example your emails occupies 250kB it will count as 3 emails for billing effects. Note that this is the total size of the email, including headers, text, subject and attachments. Also, when attachments are sent they are converted to base64 format, so they occupy some 30% more than original size (https://en.wikipedia.org/wiki/Binary_file).