'Spam' adding to my outgoing emails from Outlook

[Dezzy]

When I send an email from Outlook, it automatically adds the word 'Spam' in
the subject title. I asked my ISP if they are doing this...NO. I asked my
mail server if they are doing this...NO. In fact, if I send an email
directly from the mail server using a web/browser mail program (OpenWebMail),
I don't get the word 'Spam.' So it's not my mail server, it's not my
ISP...is it Outlook?

Thanks

Dezzy