My practice is to freely text physicians I know well about their patients. It's instantaneous, it's informal, it breeds a certain collegial connectivity that is good for business. I also like free-form written emails via our internal encrypted system. In addition, our outpatient EMR auto-creates "referral letters" to primary doctors. These get sent to the doctor's inbox as soon as I click "sign" on my office notes. These notes are really something. Not exactly an unearthed archive of F Scott Fitzgerald corresponding with Hemingway, these babies. Some computer algorithm takes your office note, chops it up into relevant blocks of transferable data and information, splices in seemingly human-sounding phrases and sentences, and then synthesizes it all back together to make it look like an actual letter. I sometimes try to type in a block of text toward the end in an attempt to personalize things but that usually just gets buried under an avalanche of x ray reports, review of system minutiae, exam findings, and various instances of tortured computer-generated syntax.
Prior to EMR and texting and instantaneous communication, most specialists had no other option but to dictate referral letters to their feeders. And for some reason it evolved that the referral letter had to be composed in this faux-formalized, knock-off Henry Jamesian diction and syntax, as if American doctors were a bunch of 18th century courtiers.