Basic examples in LN always mention payments from an online end user to other online end user. But let's say we want to send a micropayment donation to a blog that does not have an always online LN client.

With an on-chain transaction, the payer can send the money and the money will be there even if the payee can't check that within a week time. How about LN?

What are the current proposals for such payments? And what are the requirements for such end users who want to receive payments? Do we require the payee to get online at least once a day, once a week, or no such requirements are there?