Hi,
Would you please specify what kind of special characters is in the email address?
By "not accepting", do you mean you can't type these email addresses in the To filed or other meaning? Did you get any error message when Outlook refused to accept these email addresses?
If you mean you can't type these email addresses in the To field, please try adding these email addresses as contacts in your Outlook and then click To button to select these contacts.
If I've misunderstood something, please feel free to let me know.
Regards,
Steve Fan
TechNet Community Support