Curiosity got the better of me and we are testing this right now. Preheaders are cooked and a nit (don't care as much) but some email can still do preview headers by turning off line height, max width, opacity zero, etc, etc vs display:none which no longer works with P13/P4.
Costco and Walmart emails don't display properly with random images overlaying/floating on top of other images. Pretty much what we expected. So any email with lots of images could be a problem. If it is one image after another then it should be fine and I doubt anyone would notice or care... Washington Post appears to be fine as a result. Best Buy renders like it is 1997. We laughed out loud when we saw that one.
I switched it off the test machine and we retested the same emails:
Code: Select all
zmlocalconfig -e zimbra_use_owasp_html_sanitizer=FALSE
Everything looks great again.
If it was ugly that would be one thing but when you can't read the email that could be a show stopper.
It's a tough call. Certainly fixing the inline images in signatures is a strong reason to apply the patch if you have owasp enabled.