Mails may contain several "streams", like the normal text and attachments. The text however may also exist in more than just one variant. The standard allows plain text and HTML text to coexist within one mail, but in this case both parts must contain the same text, even if they are displayed differently.

Now some very smart companies, but this also applies for spam mails, decide to fill only the HTML part with their message and leave the alternative text part empty. Most mail clients on other systems prefer to display HTML text this goes unnoticed by the masses and nobody complains. Since YAM still prefers plain text over other alternatives and hence will display a mail with no body at all.

However, this can be worked around. Open the config window, go to the "Read" page and activate the options "Display all texts" and "Show alternative parts". This will let YAM display the alternative HTML part as an attachment and additionally will show this HTML part converted to text.