diff --git a/README.md b/README.md
index 67359f1d..0ae02bdf 100644
--- a/README.md
+++ b/README.md
@@ -823,7 +823,7 @@ For ex:
 }
 ```
 
-#### POST /api/v2/alias/custom/new
+#### POST /api/v3/alias/custom/new
 
 Create a new custom alias.
 
@@ -833,6 +833,7 @@ Input:
 - Request Message Body in json (`Content-Type` is `application/json`)
     - alias_prefix: string. The first part of the alias that user can choose.
     - signed_suffix: should be one of the suffixes returned in the `GET /api/v4/alias/options` endpoint.
+    - mailboxes: list of mailbox_id that "owns" this alias
     - (Optional) note: alias note
 
 Output:
diff --git a/app/api/views/new_custom_alias.py b/app/api/views/new_custom_alias.py
index bcfef52c..353f95db 100644
--- a/app/api/views/new_custom_alias.py
+++ b/app/api/views/new_custom_alias.py
@@ -21,6 +21,8 @@ from app.models import (
     CustomDomain,
     DeletedAlias,
     DomainDeletedAlias,
+    Mailbox,
+    AliasMailbox,
 )
 from app.utils import convert_to_id
 
@@ -187,3 +189,111 @@ def new_custom_alias_v2():
         jsonify(alias=full_alias, **serialize_alias_info_v2(get_alias_info_v2(alias))),
         201,
     )
+
+
+@api_bp.route("/v3/alias/custom/new", methods=["POST"])
+@cross_origin()
+@require_api_auth
+def new_custom_alias_v3():
+    """
+    Create a new custom alias
+    Same as v2 but accept a list of mailboxes as input
+    Input:
+        alias_prefix, for ex "www_groupon_com"
+        signed_suffix, either .random_letters@simplelogin.co or @my-domain.com
+        mailboxes: list of int
+        optional "hostname" in args
+        optional "note"
+
+    Output:
+        201 if success
+        409 if the alias already exists
+
+    """
+    user: User = g.user
+    if not user.can_create_new_alias():
+        LOG.d("user %s cannot create any custom alias", user)
+        return (
+            jsonify(
+                error="You have reached the limitation of a free account with the maximum of "
+                f"{MAX_NB_EMAIL_FREE_PLAN} aliases, please upgrade your plan to create more aliases"
+            ),
+            400,
+        )
+
+    hostname = request.args.get("hostname")
+
+    data = request.get_json()
+    if not data:
+        return jsonify(error="request body cannot be empty"), 400
+
+    alias_prefix = data.get("alias_prefix", "").strip().lower()
+    signed_suffix = data.get("signed_suffix", "").strip()
+    mailbox_ids = data.get("mailboxes")
+    note = data.get("note")
+    alias_prefix = convert_to_id(alias_prefix)
+
+    # check if mailbox is not tempered with
+    mailboxes = []
+    for mailbox_id in mailbox_ids:
+        mailbox = Mailbox.get(mailbox_id)
+        if not mailbox or mailbox.user_id != user.id or not mailbox.verified:
+            return jsonify(error="Errors with Mailbox"), 400
+        mailboxes.append(mailbox)
+
+    if not mailboxes:
+        return jsonify(error="At least one mailbox must be selected"), 400
+
+    # hypothesis: user will click on the button in the 600 secs
+    try:
+        alias_suffix = signer.unsign(signed_suffix, max_age=600).decode()
+    except SignatureExpired:
+        LOG.error("Alias creation time expired for %s", user)
+        return jsonify(error="alias creation is expired, please try again"), 400
+    except Exception:
+        LOG.error("Alias suffix is tampered, user %s", user)
+        return jsonify(error="Tampered suffix"), 400
+
+    if not verify_prefix_suffix(user, alias_prefix, alias_suffix):
+        return jsonify(error="wrong alias prefix or suffix"), 400
+
+    full_alias = alias_prefix + alias_suffix
+    if (
+        Alias.get_by(email=full_alias)
+        or DeletedAlias.get_by(email=full_alias)
+        or DomainDeletedAlias.get_by(email=full_alias)
+    ):
+        LOG.d("full alias already used %s", full_alias)
+        return jsonify(error=f"alias {full_alias} already exists"), 409
+
+    custom_domain_id = None
+    if alias_suffix.startswith("@"):
+        alias_domain = alias_suffix[1:]
+        domain = CustomDomain.get_by(domain=alias_domain)
+        if domain:
+            custom_domain_id = domain.id
+
+    alias = Alias.create(
+        user_id=user.id,
+        email=full_alias,
+        note=note,
+        mailbox_id=mailboxes[0].id,
+        custom_domain_id=custom_domain_id,
+    )
+    db.session.flush()
+
+    for i in range(1, len(mailboxes)):
+        AliasMailbox.create(
+            alias_id=alias.id, mailbox_id=mailboxes[i].id,
+        )
+
+    db.session.commit()
+
+    if hostname:
+        AliasUsedOn.create(alias_id=alias.id, hostname=hostname, user_id=alias.user_id)
+        db.session.commit()
+
+    return (
+        jsonify(alias=full_alias, **serialize_alias_info_v2(get_alias_info_v2(alias))),
+        201,
+    )
diff --git a/tests/api/test_new_custom_alias.py b/tests/api/test_new_custom_alias.py
index 473def92..29417ab8 100644
--- a/tests/api/test_new_custom_alias.py
+++ b/tests/api/test_new_custom_alias.py
@@ -4,7 +4,7 @@ from app.alias_utils import delete_alias
 from app.config import EMAIL_DOMAIN, MAX_NB_EMAIL_FREE_PLAN
 from app.dashboard.views.custom_alias import signer
 from app.extensions import db
-from app.models import User, ApiKey, Alias, CustomDomain
+from app.models import User, ApiKey, Alias, CustomDomain, Mailbox
 from app.utils import random_word
 
 
@@ -182,3 +182,53 @@ def test_cannot_create_alias_in_trash(flask_client):
         json={"alias_prefix": "prefix", "signed_suffix": suffix, "note": "test note",},
     )
     assert r.status_code == 409
+
+
+def test_success_v3(flask_client):
+    user = User.create(
+        email="a@b.c", password="password", name="Test User", activated=True,
+    )
+    db.session.commit()
+
+    # create api_key
+    api_key = ApiKey.create(user.id, "for test")
+    db.session.commit()
+
+    # create another mailbox
+    mb = Mailbox.create(user_id=user.id, email="abcd@gmail.com", verified=True)
+    db.session.commit()
+
+    # create new alias with note
+    word = random_word()
+    suffix = f".{word}@{EMAIL_DOMAIN}"
+    suffix = signer.sign(suffix).decode()
+
+    r = flask_client.post(
+        url_for("api.new_custom_alias_v3", hostname="www.test.com"),
+        headers={"Authentication": api_key.code},
+        json={
+            "alias_prefix": "prefix",
+            "signed_suffix": suffix,
+            "note": "test note",
+            "mailboxes": [user.default_mailbox_id, mb.id],
+        },
+    )
+
+    assert r.status_code == 201
+    assert r.json["alias"] == f"prefix.{word}@{EMAIL_DOMAIN}"
+
+    # assert returned field
+    res = r.json
+    assert "id" in res
+    assert "email" in res
+    assert "creation_date" in res
+    assert "creation_timestamp" in res
+    assert "nb_forward" in res
+    assert "nb_block" in res
+    assert "nb_reply" in res
+    assert "enabled" in res
+    assert "note" in res
+
+    new_alias: Alias = Alias.get_by(email=r.json["alias"])
+    assert new_alias.note == "test note"
+    assert len(new_alias.mailboxes) == 2