Follow up b930827b77736948cf4cb4e82b8f2296d3e014e1 - Fixes #3240 - Fixed key for microsoft migration.

lib/external_credential/microsoft365.rb

@@ -91,7 +91,7 @@ class ExternalCredential::Microsoft365
     Channel.where(area: 'Email::Account').find_each do |channel|
       next if channel.options.dig(:inbound, :options, :host)&.downcase != 'outlook.office365.com'
       next if channel.options.dig(:outbound, :options, :host)&.downcase != 'smtp.office365.com'
-      next if channel.options.dig(:outbound, :options, :user)&.downcase != user_data[:email].downcase && channel.options.dig(:outbound, :email)&.downcase != user_data[:email].downcase
+      next if channel.options.dig(:outbound, :options, :user)&.downcase != user_data[:preferred_username].downcase && channel.options.dig(:outbound, :email)&.downcase != user_data[:preferred_username].downcase
 
       migrate_channel = channel