How to list all values associated with all foreign keys in djongo

I am using djongo as database connector for mongoDB. I created two models called MailGroup and User. Every User is associated with a MailGroup. Each MailGroup can have multiple users. Now, I want to fetch all mailgroups and users in the following format

mailGroups = [
    {
        "id": 1,
        "name": "group - 1",
        "users": [
            {
                "name": "x1",
                "email": "y1"
            },
            {
                "name": "x2",
                "email": "y2"
            },
            {
                "name": "x3",
                "email": "y3"
            }
        ]
    },
    {
        "id": 2,
        "name": "group - 2",
        "users": [
            {
                "name": "a1",
                "email": "b1"
            },
            {
                "name": "a2",
                "email": "b2"
            }
        ]
    }    
]

I tried this and got only the mail groups, not the associated users with each group

mailGroups = MailGroup.objects.all()
serializer = MailGroupSerializer(mailGroups, many = True)

How do I do this? Here are my models

class MailGroup(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=255)

class User(models.Model):
    id = models.AutoField(primary_key=True)
    email = models.CharField(max_length=255)
    name = models.CharField(max_length=255)
    mailgroup = models.ForeignKey(MailGroup, on_delete=models.CASCADE)

These are my serializers:

class MailGroupSerializer(serializers.ModelSerializer):
class Meta:
    model = MailGroup
    fields = ["id", "name"]

class RecipientSerializer(serializers.ModelSerializer):
    class Meta:
        model = Recipient
        fields = ["id", "email", "name", "mailGroup"]

>Solution :

You add the users to the MailGroupSerializer:

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ['id', 'name']


class MailGroupSerializer(serializers.ModelSerializer):
    users = UserSerializer(source='user_set', many=True)

    class Meta:
        model = MailGroup
        fields = ['id', 'name', 'users']