Self hosting is golden. Sadly we already feel like we have too many services for our company's size, and the sensitivity of vulnerabilities in customer systems precludes unencrypted comms. IRC+TLS could be used but we also regularly send screenshots and such in self-destructing messages (not that an attacker couldn't disable that, but to avoid there being a giant archive when we do have some sort of compromise), so we'd rather fall back to something with a similar featureset
As a degraded-state fallback, email is what we're using now (we have our clients configured to encrypt with PGP by default, we use it for any internal email and also when the customer has PGP so everyone knows how to use that)
