Do sent emails count in bandwidth limit?

Yes. Also, if the same email is sent to multiple recipients, then the size is multiplied by the number of recipients.

If you are sending to multiple recipients then you can drastically reduce the bandwidth used by:

  1. Avoiding embedded and attached images, referencing external images instead.
  2. Avoiding file attachments, providing links instead.

You can make further reductions by either avoiding HTML completely or using only simple HTML