Original sentence: " in an x-mailer header.A number of Internet service providers, sites and organisations claim that The Bat.Many spam messages have the X-Mailer header field set to The Bat.Some ISPs set traffic filters that block messages containing "X-Mailer: The Bat.to not include X-Mailer field into the messages that they send
Edited sentence: " in the X-Mailer header.A number of Internet service providers, sites and organizations claim that The Bat.Many spam messages do have the X-Mailer header field set to The Bat.not to include the X-Mailer field in the messages that they send