I like to make screening easy and to give enough options to fit just about any circumstance. Two of the following will usually work. But they can't both be links that anyone could find and send claiming to be you. Also, if you're contacting me via an internet number or a no contract phone, please expect additional scrutiny.
A LinkedIn profile with a fairly recent photo?
Professional email? I have a second email account with no connection to the hobby for a discrete and brief exchange.
I could discretely call and ask for you at your desk through the automated attendant, dial by name system or receptionist. Even if you're not there, if your professional voicemail is accessible remotely, I could leave a message for you to retrieve.
Is there a photo of you on an organization or company website someplace?
Is there an article written by you or about you that would also lead to a photo?
Active memberships on certain hobby those boards where there has been feedback left by companions you've met.
References from two or more established companions who you've met before? Depending on the strength of the references, they may be enough by themselves.
I could take a peek at your Facebook profile.
Your Drivers license with your address (but not your city) blacked out, along with a recent selfie. Please keep in mind that while you may not know, I am aware of how easy it is to purchase a prop or theatrical ID card on the Dark Web or even the Clearnet. Thus, this alone will definitely not be enough unless you're contacting me via a phone number or email that reverse searches to you.
Work ID. Similar to the use of a drivers license. Realistic work ID cards are too easily obtained online to be considered without being combined with something easily verifiable.
If you can think of something similar to the above, but that I failed to mention, tell me about it. Maybe that will work for us.
Either way, I'm sure we'll figure it out.