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How to validate email-addresses?

Hi all,

I have a client with several shoe-shops.
Customers can leave their email-address if they want to be notified when there is a sale.
Input is validated with instr()
I am checking for @ and . (required) and also checking for spaces (not allowed).
But: A LOT (5-10%) of the addresses still are wrong; (provider doesn't exist) or email-address not valid (anymore).
When sending bulk-mail its a nasty problem to get the false addresses out of the 'mergetable'.

How are others dealing with this?
I guess I could use some kind of a 'provider'-table?
"jo*****@hotmai l.com" is OK
"jo*****@hotnai l.com" is wrong

Thanks,
Arno R
Nov 13 '05 #1
24 7121

"Arno R" <ar***********@ tiscali.nl> schreef in bericht news:42******** *************@d reader2.news.ti scali.nl...
Hi all,

I have a client with several shoe-shops.
Customers can leave their email-address if they want to be notified when there is a sale.
Input is validated with instr()
I am checking for @ and . (required) and also checking for spaces (not allowed).
But: A LOT (5-10%) of the addresses still are wrong; (provider doesn't exist) or email-address not valid (anymore).
When sending bulk-mail its a nasty problem to get the false addresses out of the 'mergetable'.

How are others dealing with this?
I guess I could use some kind of a 'provider'-table?
"jo*****@hotmai l.com" is OK
"jo*****@hotnai l.com" is wrong

Sorry for possible confusion ...
Where I say 'provider' I mean 'domain' of course.
The main problem is the string after the @

Arno R
Nov 13 '05 #2
I think the answer for this problem lies in some code which is outside the
topic of this discussion, but you might try some PHP code:

http://www.sitepoint.com/article/use...il-address-php

Linda

"Arno R" <ar***********@ tiscali.nl> wrote in message
news:42******** *************@d reader2.news.ti scali.nl...

"Arno R" <ar***********@ tiscali.nl> schreef in bericht
news:42******** *************@d reader2.news.ti scali.nl...
Hi all,

I have a client with several shoe-shops.
Customers can leave their email-address if they want to be notified when
there is a sale.
Input is validated with instr()
I am checking for @ and . (required) and also checking for spaces (not
allowed).
But: A LOT (5-10%) of the addresses still are wrong; (provider doesn't
exist) or email-address not valid (anymore).
When sending bulk-mail its a nasty problem to get the false addresses out of
the 'mergetable'.

How are others dealing with this?
I guess I could use some kind of a 'provider'-table?
"jo*****@hotmai l.com" is OK
"jo*****@hotnai l.com" is wrong

Sorry for possible confusion ...
Where I say 'provider' I mean 'domain' of course.
The main problem is the string after the @

Arno R
Nov 13 '05 #3
"Linda Burnside" <linda@nospam_b urnsidebiz.com> wrote in
news:%p******** ********@newssv r17.news.prodig y.com:
I think the answer for this problem lies in some code which is
outside the topic of this discussion, but you might try some PHP
code:

http://www.sitepoint.com/article/use...il-address-php


Is there a RegExp add-in somewhere for Access?

--
David W. Fenton http://www.bway.net/~dfenton
dfenton at bway dot net http://www.bway.net/~dfassoc
Nov 13 '05 #4
On Sat, 18 Jun 2005 22:50:40 +0200, "Arno R" <ar***********@ tiscali.nl> wrote:

"Arno R" <ar***********@ tiscali.nl> schreef in bericht news:42******** *************@d reader2.news.ti scali.nl...
Hi all,

I have a client with several shoe-shops.
Customers can leave their email-address if they want to be notified when there is a sale.
Input is validated with instr()
I am checking for @ and . (required) and also checking for spaces (not allowed).
But: A LOT (5-10%) of the addresses still are wrong; (provider doesn't exist) or email-address not valid (anymore).
When sending bulk-mail its a nasty problem to get the false addresses out of the 'mergetable'.

How are others dealing with this?
I guess I could use some kind of a 'provider'-table?
"jo*****@hotma il.com" is OK
"jo*****@hotna il.com" is wrong

Sorry for possible confusion ...
Where I say 'provider' I mean 'domain' of course.
The main problem is the string after the @

Arno R

Once a week I send messages to new listings just to thank them for their
interest. Then I delete all the addresses that bounce back. They're not worth
worrying about.

Chuck
--

Nov 13 '05 #5
> Once a week I send messages to new listings just to thank them for their
interest. Then I delete all the addresses that bounce back. They're not worth
worrying about.


This is a good idea and would work for me personally.

In the shops however this is not going to work.
-- They would have to send the mail to new listings (I can automate that ....)
-- They would have to wait for 'bouncers' (send and receive mail again)
-- They would have to search for the 'bounced' entry's and delete the mail addresses.
The personnel is simply not skilled enough to handle this.

But maybe someone at the main office could check the new entry's this way once in a while.
Thanks.

Arno R
Nov 13 '05 #6

"Linda Burnside" <linda@nospam_b urnsidebiz.com> schreef in bericht news:%p******** ********@newssv r17.news.prodig y.com...
I think the answer for this problem lies in some code which is outside the
topic of this discussion, but you might try some PHP code:

http://www.sitepoint.com/article/use...il-address-php


Thanks Linda. This is helpful but this is Windows and this is Access ...

On the command prompt > nslookup tiscali.nl gives me the following:
Server:
Address: 192.168.123.1

Name: tiscali.nl
Address: 195.241.78.68

On the command prompt > nslookup tiscoli.nl gives me the following:
Server:
Address: 192.168.123.1

*** can't find tiscoli.nl: Non-existent domain

Any idea how to use and interpret the result of this system call 'nslookup' with Access?

Arno R
Nov 13 '05 #7
David W. Fenton wrote:
"Linda Burnside" <linda@nospam_b urnsidebiz.com> wrote in
news:%p******** ********@newssv r17.news.prodig y.com:

I think the answer for this problem lies in some code which is
outside the topic of this discussion, but you might try some PHP
code:

http://www.sitepoint.com/article/use...il-address-php

Is there a RegExp add-in somewhere for Access?


If you have Windows 2000 or higher, then it's there, because it's part
of VBScript. Just reference the "Microsoft VBScript Regular Expressions
5.5" library. Otherwise, install VBSCript 5.6 from Microsoft.

Then...

public sub fx(find, findin)
Dim rx As New RegExp
Dim mx As Match
rx.IgnoreCase = True
rx.Global = True
rx.Pattern = find
rx.Execute (findin)
'this sets up a Matches collection
For Each mx In MatchCollection
Debug.Print "found " & mx.Value & "!"
Next mx
end sub

For better code than this, google on "VBScript" and "RegExp".

Basically, what you need to do is:
1) make sure the pattern of the address is correct (i.e., us**@domain.com)
2) if you need to, then get the Domain.com part, and verify that it's
"alive", i.e., "ping domain.com" or "nslookup domain.com"

I think there might be a way via SMTP to check if the account exists on
the server (if it does SMTP...), but probably not. This just *INVITES*
spammers.
Nov 13 '05 #8

There used to be a method with the mail protocal called "Verify". You
could, using the same methodology as sending mail, "dial up" a mail
server and ask the server if the address was valid.

Sadly, for legitimate users of this method, the Spammers realized that
they could use this method to send out their ... stuff ... using real
mail addresses and thus make the whole process more "real" (regardless
of it being a rather weird form of "identity theft"). So mail servers
started turning this method off, in hopes of reducing the ammount of
spam.

Some servers still have the method in place, but mostly these days, you
just get back a message meaning "Invalid Command".

Most servers won't even bounce back invalid messages anymore, as the
spammers will know that the address is invalid. (Personally, this
seems silly to me, as it would reduce the server's stress from any
further messages from that spammer, but so be it.)

The only remaining way to determine if someone gets a message (and thus
the address being valid) is to send HTML mail, hope the user will
accept that, and send a link to picture. In that link is a bit of
identifying (but otherwise useless) code fragment. You can then take
the server logs (which will show that id, and compare it to the
database of what emails were sent out to determine what emails made it
to their destination, and which didn't.

This is not a 100% certain way since quite a number of people have HTML
email turned off (and they'll see the link with it's id rather then the
picture), or will have their HTML email settings set not to
automatically retrieve pictures (they also won't see the picture and
may or may not see the link depending upon what email program they are
using), or if they've chosen to reject all HTML email, they won't even
see the message.

Another way to do this is to use the same method banks and other "high
security " needs companies are going to. The email is just a
"reminder" that the content on your site has been updated. They have
to go to your site to retrieve that content (whatever the heck it is),
log in, and then they can get at your content. By tracking who's
logging in, you'll know (sort of) what emails are getting through,
except for those users who just go to your site when ever they feel
like it on regular basis regardless of what emails you've sent them.

Arno R wrote:
Once a week I send messages to new listings just to thank them for their
interest. Then I delete all the addresses that bounce back. They're not
worth worrying about.

This is a good idea and would work for me personally.
In the shops however this is not going to work.
-- They would have to send the mail to new listings (I can automate that ...)
-- They would have to wait for 'bouncers' (send and receive mail again)
-- They would have to search for the 'bounced' entry's and delete the mail
addresses.
The personnel is simply not skilled enough to handle this.
But maybe someone at the main office could check the new entry's this way once in a while.


Nov 13 '05 #9
On 19 Jun 2005 05:10:29 -0700, "Chuck Grimsby" <c.*******@worl dnet.att.net>
wrote:
Big Snip
Most servers won't even bounce back invalid messages anymore, as the
spammers will know that the address is invalid. (Personally, this
seems silly to me, as it would reduce the server's stress from any
further messages from that spammer, but so be it.)

If the server doesn't bounce undeliverable mail, then maybe it's not important
to have those bad address in the database.

Is it possible to write code (not necessarily in Access) to examine incoming
mail for "undeliverable" ?
If so, can the original send to address be stripped out of the message and put
into a file, .txt or .xls?
Then could such a file be used to update the database?

Long and drawn out, but possibly a program (C++ ?) could be written to
accomplish the task semi-automatically. I'll bet such a program would have
commercial possibilities.

Just a wizard prodder
Chuck
--

Nov 13 '05 #10

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