HI, I am afraid you will need an app for that. There are various alternatives available on the App Store.
Most can only send email from their own custom app, but "MailShot Pro" is the first to create special group contacts which you can use like a regular contact from most of your favourite apps. Because it works from the standard Mail app too, its the only way to forward an email to a group of contacts with all attachments intact. It has the ability to rapidly import your existing address book groups, select contacts from a checklist, or to add contacts manually without going via your address book.
A free version is also available to try, restricted to much smaller groups.
Full Disclosure: I am the developer of MailShot Pro and may benefit from its sale.