There are no images or formatting in the email or strange symbols show up instead of text

There are a few reasons why this might occur:

The browser displays data saved in the cache

Clear your browser cache and delete all cookies so that your browser displays current data (rather than cached pages).

Extensions block Yandex.Mail

Yandex.Mail may not work properly due to certain browser extensions or add-ons. You can temporarily disable them to determine if this is the case. If ad blockers or antivirus extensions are causing problems with Yandex.Mail, then you can add the Mail page to the list of exceptions for that particular extension.

You are using an outdated browser

Install the latest version of your browser.