I just noticed that this specifies a GPL license - PHPMailer uses LGPL so this is not compatible with it. While it's fine to credit yourself with copyright and authorship, the copyright notice conflicts with the license terms: you need to remove 'all rights reserved' (see this discussion).

If you are ok with that, could you please add a commit changing to LGPL, or just remove the license reference since it's already covered by the project's own LICENSE file.