ignore Mail::Field::IncompleteParseError errors when mail gem can't parse header

lib/postal/message_db/message.rb

@@ -329,6 +329,8 @@ module Postal
           mail.header.fields.each_with_object({}) do |field, hash|
             hash[field.name.downcase] ||= []
             hash[field.name.downcase] << field.decoded
+          rescue Mail::Field::IncompleteParseError
+            # Never mind, move on to the next header
           end
         end
       end