FA-76565 / Email MIME structure / Member archive

Choose the MIME skeleton for an outgoing message: alternative order · case 05

The plain-text alternative is placed after the HTML one, so clients prefer plain text.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

The body is multipart/alternative(text, html) when both versions exist, the html alone when only html exists, else text. Inline images go into multipart/related with the html root first; without html they become attachments. When there are attachments the result is multipart/mixed(body, attachments...). Output is a compact string such as "mixed(alternative(text,related(html,img)),att)".

Why this case matters

Composing the wrong skeleton makes clients show images as attachments, hide the plain-text version or drop parts.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
text and html	`"alternative(html,text)"`	`"alternative(text,html)"`	Failed

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