Simply save a VCF file (contact) of your sending email address. However, keep in mind this works really well only if they are using outlook.
Since they are using google, it's a bit trickier. Google contacts can import VCF files, so I'd be sure to add some wording such as "be sure to import this contact file". I'd make a specific email for your gmail clients to include this wording and do the VCF link for outlook.