The problem is that the behavior came with the last PR. It should detect mail addresses set as placeholders, in title attributes or written freely in the text and protect against spam bots.
#39508

I can't think of an idea now how to distinguish this when the filename is in the form of an email address.

I have checked it again. It is the pattern that was not present in 4.2.6 and was included again due to Issue #39422.

I think the easiest thing to do would be to change the file name and, if possible, to generally avoid using special characters in file names.

@LukasHH
Thank you! Yes, for sure. I changed the filename immediately and it solved the issue for me. I normally check file names and never use weird characters in them but for some reason I had missed this one that was generated in ADOBE Illustrator asset export.

So only reason I posted about it here was because people in that thread in the Forum told me to. For me, the issue is solved. Please feel free to close this issue (that I suspect is not really an issue then ?).

is it not recommended practice to use @ in filenames when creating retina images?

this does sound like an undesirable breaking change in a patch release

@roland-d @fancyFranci

The same issue has been reported again with #39832 , and as stated there in the initial post at the end, it seems to be common practice for some image and vector graphics editors to add an "@" to the file name. I'll close the other issue as duplicate, so let's continue discussion here.

I've allowed myself to change the title of this issue so it contains "Email Cloaking" which makes it easier to be found when people search for it, since "Email Cloaking" is the well known name of that feature.

Thank you for the tag @brianteeman

As Brian pointed out it does seem to be common practice to use @ in filenames for retina images.

@LukasHH Could you check if we can improve the regex so that retina images are not affected?

from the theory I have found something how to exclude something if src is included in the context.
'~<[^<]*(?<!\/(src))>(*SKIP)(*F)|([\w\.\'\-\+]+\@(?:[a-z0-9\.\-\p{L}]+\.)+(?:[a-zA-Z0-9\-\p{L}]{2,24}))~iu'
regex Example
But this must still be tested in Joomla, whether it has not other side effects. I will try to find a PR.

@LukasHH Thank you.

A first local test shows me that it doesn't seem to work after all.
My idea in this line:

In the regex editor it works, but in Joomla it runs into a timeout for me.

At the weekend I will probably create a PR.

@formfranska @crystalenka please test the PR #39932

Closing as having a pull request. Please test #39932 . Thanks in advance.

@formfranska @crystalenka please test the PR #39932

Sorry, Not sure exactly what I'm supposed to do. I wasn't able to copy the text from your test article https://github.com/LukasHH/other-test/blob/main/email_cloaking_test_source.html (couldn't scroll all the way down). Complete newbie in github. Sorry ?