Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlStringHow To Check For Valid Email

Author : leatherlips
Subject : How To Check For Valid Email
Posted : 31 July 2008, 21:54
Message :

I have a page where the user enters an email address. What code would I use to make sure the email address is in a valid format? I don't need to verify it. I just want to make sure they enter something like abc@abc.com. If they don't then I want them to receive an error about the email not being valid and to go back and enter a valid one.<

Reply Author: phy1729
Replied on: 31 July 2008, 22:37
Message:

http://www.regular-expressions.info/email.html<

Reply Author: AnonJr
Replied on: 31 July 2008, 23:54
Message:

I seem to remember there was a ChkEMail function (or something similar) in inc_func_common.asp. It would be a good place to start...<

Reply Author: Andy Humm
Replied on: 26 August 2008, 10:41
Message:

AnonJr: I have had a look through inc_func_common and can not see an email validity check routine. Like you say, I am sure there is a routine, somewhere within the forum, to meet leatherlips requirement. Any further ideas please..<

Reply Author: ruirib
Replied on: 26 August 2008, 10:56
Message:

Posted sometime ago as a security fix replacement for an existing function in inc_func_member.asp:

Code:


function EmailField(fTestString) 
	set regEx = New RegExp
	regEx.Global = true
	regEx.IgnoreCase = true
	regEx.Pattern = "^[A-Z0-9._%-]+@(?:[A-Z0-9-]+\.)+[A-Z]{2,4}$"

	retVal = regEx.Test(fTestString)

	set regEx = nothing

	if Not retVal Then
           EmailField = 0
	Else
           EmailField = 1
	end if
end function

<

Reply Author: Andy Humm
Replied on: 26 August 2008, 12:09
Message:

thank u ruirib<

Reply Author: Andy Humm
Replied on: 26 August 2008, 12:55
Message:

Is there an easy way to link this function Emailfield to my input field:

response.write " <input type=""text"" style=""background-color:#F5FBF1"" name=""frommail"" size=""50"">" & vbNewLine

I have added the function to my inc_func_common and can not see how to tie the functionality together with appropriate error message to be displayed - if a user inputs a wrong email string format

The code I have on the form preview is:
frommail = trim(chkString(request.form("frommail"),"SQLString")) if frommail ="" then strError = strError & "Please enter your email address! " 'checking for blank email field
if (InStr(Request("tomail"), "@") = 0 or InStr(Request("frommail"), "@") = 0) then strError = strError & "Enter an e-mail address in the form username@domain.co.uk "

But is a user puts an email in this format humbug@xmas the routine passes, (that is the code I have)
Thank you andy

<

Reply Author: HuwR
Replied on: 26 August 2008, 13:39
Message:

The function should replace the existing EmailField function in inc_func_member.asp so you will also need to include inc_func_member.asp

you would then use it like so

if EmailField(frommail) = 1 then
'we passed so do stuff :)
else
'we failed so error
end if<

Reply Author: Andy Humm
Replied on: 26 August 2008, 18:28
Message:

Thank u HuwR<

Reply Author: Andy Humm
Replied on: 26 August 2008, 19:24
Message:

I currently do not have access to my forum files, but following Huwrs input, would this work:

if EmailField(frommail) = 0 then strError = strError & "Enter an e-mail address in the form username@domain.co.uk "
... .. end if (later)

I have gone for the =0 as all the other error messages have a link underneath to return to input form.<

Reply Author: HuwR
Replied on: 27 August 2008, 01:50
Message:

yes, that should be fine.<

Reply Author: Andy Humm
Replied on: 27 August 2008, 03:58
Message:

Huwr: Thank you, all works fine now.. next!<

Reply Author: Shaggy
Replied on: 29 August 2008, 06:43
Message:

Thanks, Rui; was looking for a RegEx address validator

<

Reply Author: ruirib
Replied on: 29 August 2008, 06:56
Message:

Originally posted by Shaggy
Thanks, Rui; was looking for a RegEx address validator

No problem

. This is not a complete solution, even if it should be fine for "normal" use.<

Reply Author: Shaggy
Replied on: 29 August 2008, 06:59
Message:

Seems to be doing the trick for me so far

What problems have you encountered with it?
<

Reply Author: HuwR
Replied on: 29 August 2008, 07:04
Message:

Originally posted by Shaggy
Thanks, Rui; was looking for a RegEx address validator

here is better one

, the one posted above does not accept all the valid characters for an email address, the one below should.
\w+([!#$%*/?|^{}`~&'+-=_]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*<

Reply Author: ruirib
Replied on: 29 August 2008, 07:05
Message:

I haven't had problems. I got it from a book or online and I remember that it stated that a couple "obscure" cases weren't contemplated. I can't remember what cases were not contemplated, but they were not relevant enough to justify a much more complex regex.<

Reply Author: Shaggy
Replied on: 29 August 2008, 07:15
Message:

Thanks, Huw; have replaced the RegEx with your one. Looks like this was the source of your one, Rui - some interesting, over-the-top alternatives in that article.
<

Reply Author: ruirib
Replied on: 29 August 2008, 07:27
Message:

Yes, Shaggy, I guess that was the one.<

Reply Author: HuwR
Replied on: 29 August 2008, 07:46
Message:

actually mine needs a slight adjustment

\w*([!#$%*/?|\^{}`~&'+-=_])*\w*@\w+([-.]\w+)*\.\w+([-.]\w+)*

it was not allowing this address a!#$%&'*+-/=?@example.com which believe it or not is perfectly valid.
there are still a few cases that won't validate, but they would be very unusual.<

Reply Author: HuwR
Replied on: 29 August 2008, 07:54
Message:

sorry, another tweak, this should be much better

[A-Z0-9!#$%*/?|\^{}`~&'+-=_]*@\w+([-.]\w+)*\.\w+([-.]\w+)*<

Reply Author: Shaggy
Replied on: 29 August 2008, 09:16
Message:

Thanks, again, Huw; will add that to the script when I get back on the other machine.
<

How To Check For Valid Email

Topic

Replies ...