Enforcing valid email address is entered

[Jon12345]

I have an online form where people put their enquiry details, including their email address.

A percentage of these people mistype their email address and don't leave a contact telephone number.

What is the best way to improve the chances that they leave a valid email address? Is it just a question of having them type in their email address twice? Does this make much difference?

Experiences and thoughts please...

Jon

[graywolf]

twice is going to catch the typo's but people who want to beat the system are always going to use something like [e-mail], even if you use something as complicated as regular expression to validate

[willybfriendly]

[zend.com...]

Best checking routine I have come across.

WBF

[plumsauce]

you could always try actually letting them use
an email client. the link can always be disguised
in some way to avoid spam harvesters.

there are some people who absolutely will not
use form based messaging which involves giving
up personal details to an anonymous form.

my own rules are that you can't have my email
unless i can have yours. at which point, i
would much rather use an email client that stores
my outbounds for future reference and followup.

if faced with a form, i just leave. if i really
need to contact the site, i go to whois data.

added:

i associate these types of forms with the typical
arrogance of dot.coms, wherein the site designer
cares not one bit about how the user might want
to do things. mandatory fax numbers? ain't got one!

++++

[Stretch]

willybfriendly, I don't do php (which I assume the script is) but I'd be interested in why that's the best you've come across. What does it do?

TIA

[willybfriendly]

First it checks the syntax to be sure it is of proper email address form.

Then it splits the email address and thecks the DNS records to assure the domain exists.

Next it gets the Mail Exchange records

Next it establishes a connection to the Mail Exchange, but only long enough to get a handshake.

At that point it assumes it is dealing with a valid email address at a valid domain with a valid Mail Exchange.

Cool!

Only runs on *nix OS. Too slow to try to use to clean up a long list of emails like I was once given by a NPO for their in-house mail list. (I new there were some bad transcriptions in that list of over 3000 names and tried this function in an effort to weed them out. Time out errors was all I got.)

WBF

[BlueSky]

i associate these types of forms with the typical
arrogance of dot.coms, wherein the site designer
cares not one bit about how the user might want
to do things. mandatory fax numbers? ain't got one!

Most resorted to using forms because of spammers. If a company's email addresses are getting spammed to death, it's very easy to miss a customer's email! It's kinda like security codes, which are also not user friendly, but many are resorting to them to get around automated scripts.

Time out errors was all I got.

PHP's default settings have a 30 second time out. You either need to raise that or cut the list down into multiple ones for processing.

[plumsauce]

there are many ways to publish an email address
that robots will miss. scripts, graphic images.

my published site addresses which are protected as
described almost never get spam,
just the private ones that are easy to guess
using dictionary lists.

added:

just how does one become a customer to miss mail
from if the email address can't be found in
the first place?

[amznVibe]

That PHP script is great! Has anyone seen a variation of it in Perl?