diff --git a/app/models.py b/app/models.py
index 42ed70e4..22ff95b7 100644
--- a/app/models.py
+++ b/app/models.py
@@ -1875,10 +1875,57 @@ class CustomDomain(db.Model, ModelMixin):
 
         return domain
 
+    @property
+    def auto_create_rules(self):
+        return sorted(self._auto_create_rules, key=lambda rule: rule.order)
+
     def __repr__(self):
         return f"<Custom Domain {self.domain}>"
 
 
+class AutoCreateRule(db.Model, ModelMixin):
+    """Alias auto creation rule for custom domain"""
+
+    __table_args__ = (
+        db.UniqueConstraint(
+            "custom_domain_id", "order", name="uq_auto_create_rule_order"
+        ),
+    )
+
+    custom_domain_id = db.Column(
+        db.ForeignKey(CustomDomain.id, ondelete="cascade"), nullable=False
+    )
+    # an alias is auto created if it matches the regex
+    regex = db.Column(db.String(512), nullable=False)
+
+    # the order in which rules are evaluated in case there are multiple rules
+    order = db.Column(db.Integer, default=0, nullable=False)
+
+    custom_domain = db.relationship(CustomDomain, backref="_auto_create_rules")
+
+    mailboxes = db.relationship(
+        "Mailbox", secondary="auto_create_rule__mailbox", lazy="joined"
+    )
+
+
+class AutoCreateRuleMailbox(db.Model, ModelMixin):
+    """store auto create rule - mailbox association"""
+
+    __tablename__ = "auto_create_rule__mailbox"
+    __table_args__ = (
+        db.UniqueConstraint(
+            "auto_create_rule_id", "mailbox_id", name="uq_auto_create_rule_mailbox"
+        ),
+    )
+
+    auto_create_rule_id = db.Column(
+        db.ForeignKey(AutoCreateRule.id, ondelete="cascade"), nullable=False
+    )
+    mailbox_id = db.Column(
+        db.ForeignKey("mailbox.id", ondelete="cascade"), nullable=False
+    )
+
+
 class DomainDeletedAlias(db.Model, ModelMixin):
     """Store all deleted alias for a domain"""
 
diff --git a/migrations/versions/2021_092018_cf1e8c1bc737_.py b/migrations/versions/2021_092018_cf1e8c1bc737_.py
new file mode 100644
index 00000000..07510745
--- /dev/null
+++ b/migrations/versions/2021_092018_cf1e8c1bc737_.py
@@ -0,0 +1,51 @@
+"""empty message
+
+Revision ID: cf1e8c1bc737
+Revises: d8c55e79da54
+Create Date: 2021-09-20 18:14:17.798925
+
+"""
+import sqlalchemy_utils
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'cf1e8c1bc737'
+down_revision = 'd8c55e79da54'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('auto_create_rule',
+    sa.Column('id', sa.Integer(), autoincrement=True, nullable=False),
+    sa.Column('created_at', sqlalchemy_utils.types.arrow.ArrowType(), nullable=False),
+    sa.Column('updated_at', sqlalchemy_utils.types.arrow.ArrowType(), nullable=True),
+    sa.Column('custom_domain_id', sa.Integer(), nullable=False),
+    sa.Column('regex', sa.String(length=512), nullable=False),
+    sa.Column('order', sa.Integer(), nullable=False),
+    sa.ForeignKeyConstraint(['custom_domain_id'], ['custom_domain.id'], ondelete='cascade'),
+    sa.PrimaryKeyConstraint('id'),
+    sa.UniqueConstraint('custom_domain_id', 'order', name='uq_auto_create_rule_order')
+    )
+    op.create_table('auto_create_rule__mailbox',
+    sa.Column('id', sa.Integer(), autoincrement=True, nullable=False),
+    sa.Column('created_at', sqlalchemy_utils.types.arrow.ArrowType(), nullable=False),
+    sa.Column('updated_at', sqlalchemy_utils.types.arrow.ArrowType(), nullable=True),
+    sa.Column('auto_create_rule_id', sa.Integer(), nullable=False),
+    sa.Column('mailbox_id', sa.Integer(), nullable=False),
+    sa.ForeignKeyConstraint(['auto_create_rule_id'], ['auto_create_rule.id'], ondelete='cascade'),
+    sa.ForeignKeyConstraint(['mailbox_id'], ['mailbox.id'], ondelete='cascade'),
+    sa.PrimaryKeyConstraint('id'),
+    sa.UniqueConstraint('auto_create_rule_id', 'mailbox_id', name='uq_auto_create_rule_mailbox')
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('auto_create_rule__mailbox')
+    op.drop_table('auto_create_rule')
+    # ### end Alembic commands ###