The preview
The preview on the right of the editor is rendered by the sending engine itself, with sample values (Ada Lovelace, ada@example.com). It refreshes half a second after the last keystroke.
When the content cannot be rendered (invalid MJML, a damaged block document), the preview shows the error instead of the e-mail.
Check the links
Check the links calls every link in the content and shows its response code. A link in error (404, 500, unreachable) appears in red. Links to internal or private addresses are not called.Check for readers
Check for readers reads the rendered e-mail back and points out what gets in the way. They are remarks, never a block: each is marked Problem or Worth a look.
“Nothing in the way. This e-mail reads well.” means all is well.
What a spam filter would hold against it
The same button also reads the e-mail the way a filter does — filters are moved by what an e-mail looks like, not by what it means. These remarks come first:A link whose words are an address —
www.example.com — is not sent through click tracking: it would show one address and lead to another. It goes where it says, and its clicks are not counted. To count them, make the words something else: “See the shop”.