Links containing two @ signs can't be added

[bbastin]

Describe the bug
Links with two @ signs, like mailto:test1@example.com,test2@example.com or mailto:test1@example.com?cc=test2@example.com, are not accepted when entered into the Edit Link field.

To Reproduce
Steps to reproduce the behavior:

1. Go to Edit Page
2. Add/select text to add link to
3. Click Edit Link
4. Enter URL
5. Press right pointing arrow to save

Expected behavior
The URL is accepted and the link is now set to the specified URL.

Software (please complete the following information):

• OS: Arch Linux
• Browser: Firefox 131.0.3
• Volto Version ?
• Plone Version ?
• Plone REST API Version ?

I currently do not have access to this information, but I also verified it on the demo system. I can provide this information later on if necessary.

Additional context
It works when using percent encoding to mask the second @ sign (e. g. mailto:test1@example.com?cc=test2%40example.com, leading me to suspect that the URL parser is incorrectly parsing the second @ sign as the userinfo delimiter and gets confused.

[Faakhir30]

I saw this thing, this bug would only occur when links starts with mailto: , this is because the volto's email regex check doesn't deals for cc, bcc, multiple receiver, body, subject and so on...

Doing all these checks in regex, is not possible in my opinion, we'll need to allow multiple repitions of email groups at multiple places with a valid order and valid formats.

Or maybe some REGex Chad developer could do this with regex.

One simpler approach would be sort of compromise check for cc and multiple receiver, i.e., allow user to enter mailto:test1@example.com,{anything} or mailto:test1@example.com?cc={anything}. This wont be safe tough.