diff --git a/app/models.py b/app/models.py
index 95f56614..0be35156 100644
--- a/app/models.py
+++ b/app/models.py
@@ -253,6 +253,9 @@ class User(db.Model, ModelMixin, UserMixin):
     sender_format = db.Column(
         db.Integer, default="0", nullable=False, server_default="0"
     )
+    # to know whether user has explicitly chosen a sender format as opposed to those who use the default ones.
+    # users who haven't chosen a sender format and are using 1 or 3 format, their sender format will be set to 0
+    sender_format_updated_at = db.Column(ArrowType, default=None)
 
     replace_reverse_alias = db.Column(
         db.Boolean, default=False, nullable=False, server_default="0"
diff --git a/migrations/versions/2021_012620_85d0655d42c0_.py b/migrations/versions/2021_012620_85d0655d42c0_.py
new file mode 100644
index 00000000..6b2ce47b
--- /dev/null
+++ b/migrations/versions/2021_012620_85d0655d42c0_.py
@@ -0,0 +1,29 @@
+"""empty message
+
+Revision ID: 85d0655d42c0
+Revises: 74906d31d994
+Create Date: 2021-01-26 20:09:13.949591
+
+"""
+import sqlalchemy_utils
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '85d0655d42c0'
+down_revision = '74906d31d994'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('users', sa.Column('sender_format_updated_at', sqlalchemy_utils.types.arrow.ArrowType(), nullable=True))
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column('users', 'sender_format_updated_at')
+    # ### end Alembic commands ###