The best part is probably that she's getting Shuuko and Frederica to troll the other girls simultaneously with no setup. Shiki really is a genius.
(There have been attempts to transmit smells over data lines, but they depend on triggering a source of the scent at the receiving end, of course — little perfume vials, basically. I do wonder if you could do something like universal scent triggering with programmable matter — nanoscale computing modules that mimic atoms by reproducing their electron shells, then form into molecules — though there are obvious health worries about snorting something like that. Long-term, electrical or magnetic stimulation of either the olfactory nerves or the brain itself is a possibility; researchers have done this in a limited way in 2018, as a study into the feasibility of a kind of implant to restore the ability to smell to those who have lost it, a kind of nasal version of the cochlear implant.)
Yes, I suppose I should have specified that the use of smartphones as transmitting devices is really what makes it impossible. While it is possible to recreate a scent using information sent electronically, the devices we use to send and receive data don't provide for such functionality. In addition to the methods you listed, it is also conceivable that smells could be transmitted using visual or auditory cues in the future through synesthesia. It's not known exactly how synesthesia develops in individuals but theories suggest it could be learned.
Looks like Shiki-chan went to the hot spring...Oh.A disappearance trip huh♪ It looks like an expensive inn!Let's reply with all the fun we're having here too.Cut it out....*takes picture*Ohhhh... So stylish....Because Shiki's in a private bathing room, she can do whatever she wants. Using the the aromas she's made and fully enjoying the best scents... That's Shiki for you.Sniff sniff....Woah♪As expected, this is a nice fragrance...♪Sending a scent file☆*breathes in*Ranko-chan wants to smell as well? Here's the sent scent~How did you make such a collaboration without a prior meeting!?I smell it...maybe?Since Professor Shiki is a genius, she can data-ify fragrances y'know.EEEEEEEEEHHH!?Actually, I didn't send a fragrance after all. If I decieved you, I'm sorry, sooooorrry☆ Just having fun with a placebo♪