Personalize emails with recipient's first name on iPad

There is no built-in mail-merge function in Mail.app.

However, it is possible to craft an Automator action to do this, even with the abysmal Automator interface. Here's an example:

Specifically:

Action 1: Find Contacts

You can add any conditions you like to filter the list of people whom you want to email.

Action 2: Repeat

This initiates a loop through the contacts retrieved in step 1

Action 3: Text

This is where you craft your email message.

When you get to where you want the recipient's name, you should have a list of variables at the bottom of your iPad screen... click on Repeat Item (so that it knows you want to use the current iteration's value), then choose First Name.

Action 4: Send Email

This creates the email using the text from the previous step as the message body. You can set the Subject line.

The tricky part (which Automator's UI does not make easy/intuitive) is in setting the recipient's address. When you tap on the default 'to' field it will want you to type an address... instead, what you need to do is delete this field altogether, then long-press on the Recipients field and choose Select Variable... from the menu that (should) appear. Now you have to tap 'Repeat Item' that will appear below Action 2 to tell it that you want to use some element of the current iteration, then tap it again once it's applied to the Action to choose 'Email addresses' from the available fields.

If you turn off the 'Show Compose Sheet' it will send the message automatically, otherwise it will show the message and you'll need to confirm that you want to send it (useful for testing).

Note that if the contact has multiple email addresses sent, the message will be sent to all of them. If this is a problem you can add a step to extract the first item from the list, but hopefully that won't be necessary.