That is strange. I personally haven’t seen this happening with Mac OS Catalina, Big Sur or Monterey using the latest V8.2.1687.
If this happens on every email, i would maybe suggest to “try an older version” of eM Client for Mac being El Capitan is a very old OS now and no longer supported by Apple and could be the latest version of EMC for Mac is not designed for that older OS.
Another user on this forum who had El Capitan said V8.2 (1478) seems to work ok, so maybe suggest to uninstall your current version and try this version from the version history page
If this issue happens with “only specific emails”, it might be the “senders email client” that might possibly be incompatiable in some way with eM Client. Do you know which email client they use ?.
I would even suggest for your older Mac OS is to (try the latest version 7.x) of eM Client if you cannot get any V8.x to work correctly from the version history page. See if that fixes the issue.
(Latest version 7 eM Client for Mac)
Monday, February 24, 2020
eM Client for Mac 7.2 Service Update
- Fixed occasional crashes during scrolling
- A few other fixes