Free 7 day trial and then you have to pay. No mail client support. Claims to encrypt metadata and senders instead of just messages. Blog and support forum appear pretty dead; FAQ is also outdated - says Scryptmail is only a year old, but it's actually 4.
What about the privacy? Website uses Matomo analytics described in ProtonMail's section. And the mail? According to their privacy policy, whenever two Scryptmail accounts communicate, only "sent times" metadata is stored. On the other hand, if someone using another provider sends an e-mail to your Scryptmail account, the collected data extends to this:
sender and recipient email addresses, the IP address incoming messages originated from, message subject, body and attachments and message sent and received times.
Other stored information includes: "Last login time, IP address, User agent, API call." Though they claim that they "have no ability to match an IP to a specific user account." Which appears to contradict the earlier claim, since they know when a certain account logged in, as well as with which IP address. It is possible they delete the information about the account which the data belongs to, but to say that they have "no ability" to connect them is a lie.
You should assume that your data will be stored pretty much forever. From the Data Retention section: "Active accounts will have data retained indefinitely." What about deleted accounts?
Your personal data shall be deleted no later than at the end of the calendar year following the year of the termination of the contract unless in an individual case specific reasons to the contract apply. [...] Moreover, the deletion of inventory and billing data may be omitted provided that legal regulations or the prosecution of claims require this action.
In summary: paid, no mail client support, confusing and contradictory privacy policy, significant amount of data stored and never deleted. Avoid!