Multiple email addresses in a single contact
You can create email or contact based groups with those contacts using the stock Mail app. But you will need iCloud on the web to make those groups.


First of all, you need to make sure your contacts are being backed
up in iCloud. Go to Settings > 'Mail, Contacts, Calendars' and
select iCloud from the Account at the top. make sure Contacts has a
green slider next to it.
Now log into www.icloud.com using your Apple ID, and select Contacts.
You'll see all the contacts from your iPhone presented in a list. Click the + icon at the bottom of the lefthand pane. Select New Group.
The new group, called Untitled Group 1 for the time being, appears in the lefthand column below All Contacts. Name the group and click outside the box to save it. (If you change your mind and decide to delete a group, you need to make sure the group is highlighted and then click the cog icon at the bottom left and click Delete.)
Go back to the All Contacts group and decide who you want to add to your new group. You can add contacts individually by dragging-and-dropping their names on to the new group.
If you want to remove a name from a group, you need to be in the group, with the name of the group highlighted, and the name of the soon-to-be-removed contact highlighted too. Then click the cog and select Delete. This will just remove the name from the group (with no warning popup, incidentally), rather than deleting it from your contacts entirely. You'll know if you've got this wrong, because it you tell iCloud to delete a contact completely you will get a warning and have to select Delete a second time to confirm this.)
You can batch-add contacts to speed up the process. Click and hold the Command button (also known as the Apple button) and then click each contact you want to add, in turn. These will all be selected simultaneously. (If you get one wrong, click it again to remove it from the selection.) Now release Command and click-and-drag any one of the highlighted names on to the new group, and the other selected names will be brought along for the ride. For really fast adding, you can hold down Shift instead of Command, then click on two names. iCloud will select every contact that sits between the two alphabetically.
Close down the tab with iCloud in and open up your iPhone. Launch Contacts, and tap Groups at the top left of the screen. The new group will be listed under iCloud. By default all of the groups on the screen will be ticked, but if you tap the new group's name all the other groups will be untucked, leaving just the new one. Now tap done, and you'll see a list of contacts in the new group. (In our experience the new group appears almost instantaneously, provided you've got an internet connection. There's isn't a significant syncing delay.)
You can now send an email to the whole group very easily. Open Mail and create a new message. In the To field, start typing the name of the group, and iOS will offer it as a suggestion. Tap the group (labelled, in our experience, as just 'Group', rather than its full name) to insert all the email addresses as recipients. You can remove recipients individually if you want to send an email to most of the members of a group.




There is a way of creating an email group on the iPhone itself, but it's a bit of a fudge - effectively you're creating a new contact which has multiple email addresses crammed together.


Open the Contacts app.
Tap the Add (+) icon.
Enter the name of the group (such as "friends" or "work") in the Last field.
Scroll down to the Notes section. We're going to use this to write out the email addresses. You need to surround each mail address with greater than and less than symbols and place a comma between each one. For example , .
Tap and hold the names to bring up the contextual menu. Tap Select All and Copy.
Tap Add Email.
Tap and hold the Email field and tap Paste.


That now creates a contact with a single name but multiple email addresses. Open the Mail app and tap New. Now enter the name of the group into the To field. It will turn blue, indicating that it is a contact. When you send the email it will go to all the people whose email addresses you added to Contacts.

Source and images for both solutions: MacWorld