Can I refer to myself as doctor in my signature?

Guidance for Academic Signature Blocks

In summary, there are two general rules for academic/professional communications, which includes e-mail signature blocks: (1) only include the degree and credentials that you have earned, and (2) when in doubt about what to include, less is generally more. Specific contexts outside of Walden University may require a different strategy, however, so try to model your signature on professionals at the same level of training in that context.    

For more information, review the following links: