Self Reference: Send a pigeon, send a fax...

Messaging through non-traditional means

Conditions:
Assumes there is a set of code phrases, or protocols in place. And that the person in question isn't completely off the grid.

There is always the chance that the code can be noticed, or broken. So risk assessment.

1. If the address of the person is unknown, they don't have a permanent address, or cannot be reached any other way.

( ... )

2. If the person sending the message may not be able to personally do so (the In-case-of situation):

( Three men can keep a secret if two of them are dead. - Benjamin Franklin )

3. Knowing there may be a need to split up and run (with a pre-planned meet up or not):

( ... )

If you can think of any more, tell me, I would love to know!