Is there any way of telling if an e-mail address is valid without
sending a message to the e-mail address?

Mongolia

Hello mongolia,

Thanks for the question. The answer is yes, you can.

For example, this site says:

"...EMail Address Checker

This checks EMail addresses in real time. Use it to check the
authenticity of an email address.

Key features

Checks whether a mail box / email exists 
E-mails are not sent during checks 
Shows MX records for the email address domain (requires you to login) "

http://www.broadband-help.com/tools/email-check/default.aspx

And, there are numerous programs you can download for this as well.
This one is $39.95, but has a free trial period:

"...eVerify
validate email addresses
Our Rating:  (Very Good) 

eVerify can be used to verify e-mail addresses in your mailing lists
or database fields. eVerify does not actually send any messages to the
email address to be validated, but only connects to the server to
check whether the email address exists or not. The program can import
addresses from various file types, as well as the Windows Address Book
(WAB) and any ODBC data source. It includes a query wizard to makes
importing from ODBC very easy without the need to know any SQL. Once
the list is loaded, you can choose to check all or selected entries
and the results are color code in the display. eVerify offers rules
that let you customize the way certain responses from the mail server
are handled. You can also use rules to validate the syntax of email
addresses and automatically mark email as invalid that match specified
criteria. Additional features include scheduled validation, database
updates via ODBC, selective logging, Socks5 proxy support and more..."

http://www.snapfiles.com/get/everify.html


There are also numerous sites with code to be inserted in your own
applications to verify email addresses without sending an actual
email. Just google "verify email address" for numerous hits.

I trust my research has provided you with the answer you desired. If a
link above should fail to work or anything require further explanation
or research, please do post a Request for Clarification prior to
rating the answer and closing the question and I will be pleased to
assist further.

Regards,

-=clouseau=-

Howdy Clouseau

I guess my final question and answer(sob sob).
All the best for the future

DPRK007
DPRK
007
MONGOLIA
MAGNOLIA
MONGO
:-(  and :-)

Well I just tried out :
http://www.broadband-help.com/tools/email-check/default.aspx

And to my interest, found that my Email address 'is not a valid email address'
The address is my domain name, Emails are diverted to my ISP address
by my web space supplier.

When I checked my ISP address xxxx(at)btconnect.com 
I was told that, that was also 'not a valid email address'

I would be wary about using that.

Actually the question recently came up in a programming News Group,
and the consensus was that it could not be done, although I am pretty
certain that one could do it in the past.

I tried a few legitimate email addresses at
http://www.broadband-help.com/tools/email-check/default.aspx also.

Found NONE of them to be  "valid".

I'm not sure how they are doing the check, but it isn't acurate.

Indeed, may be my final answer.

Thanks for the stars and tip. And keep the faith. This hardy bunch of
researchers just may surface again one day on a monitor near you.

Happy holidays,

-=clouseau=-