This is actually my biggest concern, so no offense taken:
Despite Google's privacy policy and ad behaviour (yadda yadda), they ARE still a trustworthy company, regarding uptime , backups and everything technical. Though I remember them losing quite a few accounts about a year back. But still, your point is very valid. Why would anyone trust a small company (or even single hacker) to maintain your precious emails.
* A very straightforward exit strategy: make it easy for users to at least extract their mail from your service, if they host it on your servers, and want to have an offline backup.
* Offer an option to license for self-hosting: hosting their own email could take away their fear of uncontrollable downtime.
Despite Google's privacy policy and ad behaviour (yadda yadda), they ARE still a trustworthy company, regarding uptime , backups and everything technical. Though I remember them losing quite a few accounts about a year back. But still, your point is very valid. Why would anyone trust a small company (or even single hacker) to maintain your precious emails.