The way you send an email to a group of people from an iDevice is not that obvious. I tried a lot of different ways that didn't work. I'll describe here the way I found to do it that does work.
Create a text document with nothing but the email addresses separated by commas and nothing else.
It should look something like this: firstname.lastname@example.org,email@example.com,firstname.lastname@example.org
Copy the text and paste it into the To: box.
When you leave the box, it will say "1 recipient". But if you save the email as a draft and come back to it, it will say the correct number of recipients, and you can "click" or touch the description and the list of the recipients will appear as separate buttons as you would expect they should.