Rendering: Email addresses don't start with a special char (do they?)

[nschloe]

Description

Related to #27616.

Email addresses can only start with an alphanumeric character. Hence these are not valid email addresses:

?a@example.com
~a@example.com
*a@example.com
~a@example.com

However, Gitea renders them as such:

The mailto link should only start at the a. GitHub handles this correctly:

?a@example.com
~a@example.com
*a@example.com
~a@example.com

Gitea Version

1.22.0+dev-262-gec0c6829d

Can you reproduce the bug on the Gitea demo site?

Yes

Log Gist

No response

Screenshots

No response

Git Version

No response

Operating System

No response

How are you running Gitea?

https://try.gitea.io/

Database

None

[dek5troza]

Hi, I would offer my time to help fix this, if this is something suitable for first timer to gitea?

[lng2020]

Hi, I would offer my time to help fix this, if this is something suitable for first timer to gitea?

Seems like a good first issue. Changing the regexp and adding a test like this PR will probably solve the problem.

[dek5troza]

Thanks for the pointer. I will take care of it, you can assign it to me if you want.

[dek5troza]

Sorry for the delay. I modified the regular expression to allow emails only to start with alphanumeric character, and few test cases from the bug report, validating that these are no longer rendered as valid email addresses. Please let me know, if anything needs update, or if I have missed something, and I ll take care of it.

[wxiaoguang]

FYI: actually ~a@a.com and *a@a.com are valid email addresses ....... so it's hard to say "GitHub is right" .....

func main() {
	a, _ := mail.ParseAddress("~a@b.com")
	println(a.Address)
	a, _ = mail.ParseAddress("*a@b.com")
	println(a.Address)
}

Output:
~a@b.com
*a@b.com

[lng2020]

According to https://stackoverflow.com/questions/201323/how-can-i-validate-an-email-address-using-a-regular-expression, ~a@a.com and *a@a.com are valid email addresses.
But interestingly Gmail doesn't render it either. Seems like both GitHub and Gmail use more strict rules for rendering.

[wxiaoguang]

I have no preference for either choice.

But if we'd like to improve it, it needs enough comments and test cases to document the behavior and how the decision was made.