Freron MailMate

I write all my email in Markdown, and I have MailMate set to create and send its simple, syntactically correct HTML version of the Markdown automatically.

But for some weeks now, if I “save” the message at any point before sending it, I see an orange bar across the top of my composer pane, with the message “Generating HTML failed.”

Until recently, if I had preview pane visible, the HTML preview (which had looked just fine!) would then be replaced by a plain-text preview; and, interestingly, any further changes to the composer pane would result in the preview pane instantly reverting to a very fine looking HTML preview.

As of the current test version of MailMate (well, r5864 & r5865 anyway), however, the preview pane consistently shows the HTML version of my Markdown throughout all the steps I’ve listed above.

It looks to me as if the HTML generation always fails: if I send myself an e-mail with Markdown markup, whether I save it first (thereby eliciting the dread orange banner) or not, the message that I receive has only one MIME section:

Content-Type: text/plain; markup=markdown

*This* is another test!

and no HTML section.

Though at heart I truly believe in text-only e-mail, I fear that ship has long since sailed — and I need many of my correspondents to see actual italics, bolds, and (especially) blocked-off code snippets in a monospaced font.

Does anyone have any ideas about why the HTML conversion is no longer working for me? One possibility that’s occurred to me is that I may have (years and years ago!) customized the CSS.... But I can’t figure out where that custom CSS might be hidden, and so I can’t remove it to test....

Many thanks for any pointers!