Depends on your needs. It’s reasonable for mails you don’t need instantly or offline, but at the same time should be encrypted at rest. I don’t know if there is a new pricing model now, but I have paid 1€ a month, so basically nothing. If you don’t mind the downsides and encryption is important to you, it’s a very fair price I think.
Would you recommend it as a secondary service?
Depends on your needs. It’s reasonable for mails you don’t need instantly or offline, but at the same time should be encrypted at rest. I don’t know if there is a new pricing model now, but I have paid 1€ a month, so basically nothing. If you don’t mind the downsides and encryption is important to you, it’s a very fair price I think.