diff --git a/app/models/incoming_email.rb b/app/models/incoming_email.rb
index 66d7053fddb..0eec96f162f 100644
--- a/app/models/incoming_email.rb
+++ b/app/models/incoming_email.rb
@@ -6,6 +6,8 @@ class IncomingEmail < ActiveRecord::Base
   belongs_to :post
   belongs_to :group, foreign_key: :imap_group_id, class_name: 'Group'
 
+  validates :created_via, presence: true
+
   scope :errored,  -> { where("NOT is_bounce AND error IS NOT NULL") }
 
   scope :addressed_to, -> (email) do
@@ -33,6 +35,7 @@ class IncomingEmail < ActiveRecord::Base
 
   def self.created_via_types
     @types ||= Enum.new(
+      unknown: 0,
       handle_mail: 1,
       pop3_poll: 2,
       imap: 3,
@@ -106,7 +109,7 @@ end
 #  imap_uid          :integer
 #  imap_sync         :boolean
 #  imap_group_id     :bigint
-#  created_via       :integer
+#  created_via       :integer          default(0), not null
 #
 # Indexes
 #
diff --git a/db/migrate/20210121001720_change_incoming_email_created_at_null.rb b/db/migrate/20210121001720_change_incoming_email_created_at_null.rb
new file mode 100644
index 00000000000..b751a927769
--- /dev/null
+++ b/db/migrate/20210121001720_change_incoming_email_created_at_null.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class ChangeIncomingEmailCreatedAtNull < ActiveRecord::Migration[6.0]
+  def up
+    # 0 signifies unknown
+    DB.exec("UPDATE incoming_emails SET created_via = 0 WHERE created_via IS NULL")
+    change_column_default :incoming_emails, :created_via, 0
+    change_column_null :incoming_emails, :created_via, false
+  end
+
+  def down
+    change_column_null :incoming_emails, :created_via, true
+  end
+end
diff --git a/lib/email/receiver.rb b/lib/email/receiver.rb
index 2b9ecfe5140..ac0dc509db5 100644
--- a/lib/email/receiver.rb
+++ b/lib/email/receiver.rb
@@ -153,7 +153,7 @@ module Email
         imap_uid: @opts[:imap_uid],
         imap_group_id: @opts[:imap_group_id],
         imap_sync: false,
-        created_via: @opts[:source].present? ? IncomingEmail.created_via_types[@opts[:source]] : nil
+        created_via: IncomingEmail.created_via_types[@opts[:source] || :unknown]
       )
     end
 
diff --git a/spec/fabricators/incoming_email_fabricator.rb b/spec/fabricators/incoming_email_fabricator.rb
index 06a08b129de..de76343f815 100644
--- a/spec/fabricators/incoming_email_fabricator.rb
+++ b/spec/fabricators/incoming_email_fabricator.rb
@@ -6,6 +6,7 @@ Fabricator(:incoming_email) do
   from_address "foo@example.com"
   to_addresses "someone@else.com"
   imap_sync false
+  created_via 0
 
   raw <<~RAW
     Return-Path: <foo@example.com>