Authentication alone is not enough
SPF, DKIM and DMARC answer the question of who sent a message. Whether it lands in the inbox or the spam folder additionally depends on how it is constructed. Filters like SpamAssassin and Rspamd assign points for structural irregularities in the body — and many of those arise accidentally at perfectly legitimate senders.
What AnalyzeMy.Email checks
- Missing plaintext part: an HTML-only message without a
text/plainalternative is a classic spam characteristic. Properly built mailers send both parts asmultipart/alternative. - Tracking pixels: images one or a few pixels across whose only purpose is open tracking.
- Hidden text: content with
display:none, zero font size, or font colour equal to the background — originally a technique for feeding filters invisible words. - URL shorteners: shortened links obscure the destination and are scored accordingly.
- Image-to-text ratio: messages consisting almost entirely of one large graphic cannot be evaluated by filters and are therefore treated with suspicion.
Why these signals carry weight
The underlying logic is always the same: each of these characteristics either hampers a filter's content evaluation or was historically an evasion attempt. A message consisting only of an image cannot be checked for textual features — which is precisely why spammers used it, and precisely why the rules against it remain strict today.
This is awkward for legitimate newsletters, since graphics-heavy design and open tracking are industry standard. But the points add up: a tracking pixel alone tips nothing; a tracking pixel plus missing plaintext plus 90 percent image content plus a shortener link certainly can.
Concrete improvements
- Always send both parts. A genuine, readable plaintext version — not just a placeholder saying "this message requires HTML".
- Increase the text share. As a rule of thumb, a message should remain comprehensible with images disabled.
- Set alt texts — this helps filters and screen readers alike.
- No shorteners in business email.
- Avoid hidden text, including the well-intentioned preheader. If you use one, do it through the technique designed for it.
- Unsubscribe link and legal footer in newsletters — where these are missing, some filters score it negatively, quite apart from the legal requirement.