Looks to me like no: <a href="https:&#x2F;&#x2F;tutanota.uservoice.com&#x2F;knowledgebase&#x2F;articles&#x2F;470785" rel="nofollow">https:&#x2F;&#x2F;tutanota.uservoice.com&#x2F;knowledgebase&#x2F;articles&#x2F;470785</a><p>There is some voodoo in there about them storing your unencrypted mail encrypted on their server, but from that diagram it looks like it&#x27;s only end to end between people registered with Tutanota (it looks like they may also allow federation, since they mention &quot;or another service&quot;).