That's true.
https://www.neomailbox.com/about/transparency
Transparency Report
Neomailbox Warrant Canary
The following statement is true on October 1st, 2017: Neomailbox has never released any customer data to any government agency or other entity.
This statement will be updated on the 1st of every month. Exercise caution if this page disappears, changes significantly in content, or is outdated.
Statistics on electronic surveillance by the Swiss Post and Telecommunications Surveillance Service for past years covering all of Switzerland can be found via the links below.
2014: Realtime Internet surveillance: 12 cases, Metadata requests: 18 cases 2013: Realtime Internet surveillance: 21 cases, Metadata requests: 32 cases
Neomailbox seems to have an auto detection / deletion feature for spam... it needs further investigation to see how well this is done (source )
It's based in Switzerland - although recently I believe they have had a change of law in regards to data-retention and seems to be experiencing pressure for a tide-change on privacy policies (don't quote me on this, I can't remember the few places I read this!)
That One Privacy Site seems to give it a good rating on the whole
They support IMAP but no mention of CalDAV so not sure on that front.
Paid Hushmail alternatives with PGP integration that don't suck:
More (free and paid): https://www.reddit.com/r/emailprivacy/wiki/index#wiki_free_privacy_friendly_clearnet_email_services