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Posted 21 Feb 2002


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MultiMail 2.0 - Freeware SMTP stress testing tool

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4.79/5 (32 votes)
3 Oct 20032 min read
This free program can be used to stress test SMTP servers. It also aids anti-Spam tool developers as a useful mail-bombardment tool.

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About MultiMail 2.0

MultiMail 2.0 is a multi-threaded SMTP stress testing program which also doubles up as a handy tool for anti-Spam software development. It starts multiple threads, each sending a large number of mails in parallel to a specified SMTP server. MultiMail 2.0 is  freeware and can be used by anyone without the author's explicit permission.

How it came about?

Version 1.0

I wrote the first version while I was developing my own anti-Spam program Pop 3 Protector (discontinued). I used it to bombard test POP accounts with a large amount of email from multiple fake email addresses and with multiple subject headers.

A few months ago [here the current time is Feb 2002], I was asked to try out three different Linux based SMTP servers and decide on the fastest one. That's when I got a chance to use this tool once again. I sent huge amounts of mail through each server and recorded connection and mail delivery speeds. To increase the load I made the program multi-threaded. The user can set the number of threads to use. In this particular version I have restricted this number to 10, to prevent malicious people from misusing this program. But for anyone who wants to use this as an SMTP stress tester, 10 threads running in parallel, each thread sending 1000 mails each, should be quite good enough.

Actually there is a sneaky way to over-ride the restrictions, which is by running multiple instances of the program. But for some strange reason I have noticed that this will considerably slow down the user's machine and I hope that will deter people from trying it out.

Version 2.0

Version 2.0 uses the ATL7 SMTP and MIME classes and so I have removed all my Winsock-SMTP-chat code from the program. This has enabled me to add support for attachments which is quite handy.

Sending mail using the ATL7 classes

  • Include the required header file
  • #include <span class="code-keyword"><atlsmtpconnection.h></span>
  • Call CoInitialize
  • CoInitialize(0);
  • And write code similar to below snippet
  • CMimeMessage msg;
    CSMTPConnection conn;
    BOOL bSuccess = conn.SendMessage(msg);
  • Call CoUninitialize
  • CoUninitialize();


  • v1.0 - 22 Feb 2002
  • v2.0 - 05 Oct 2003


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here


About the Author

Nish Nishant
United States United States
Nish Nishant is a Principal Software Architect based out of Columbus, Ohio. He has over 17 years of software industry experience in various roles including Lead Software Architect, Principal Software Engineer, and Product Manager. Nish was a Microsoft Visual C++ MVP between 2002 and 2015.

Nish is an industry acknowledged expert in the Microsoft technology stack. He authored C++/CLI in Action for Manning Publications in 2005, and had previously co-authored Extending MFC Applications with the .NET Framework for Addison Wesley in 2003. In addition, he has over 140 published technology articles on and another 250+ blog articles on his WordPress blog. Nish is vastly experienced in team management, mentoring teams, and directing all stages of software development.

Contact Nish : If you are interested in hiring Nish as a consultant, you can reach him via his google email id voidnish.

Company Website :

Comments and Discussions

GeneralMy vote of 5 Pin
Member 826594610-Jun-12 14:27
MemberMember 826594610-Jun-12 14:27 
QuestionBig thatks Pin
Misiu8-Mar-12 4:01
MemberMisiu8-Mar-12 4:01 
QuestionSource code Pin
jnks20054-Sep-07 6:28
Memberjnks20054-Sep-07 6:28 
Questionregarding the number of connections established Pin
lp19823-Sep-07 0:15
Memberlp19823-Sep-07 0:15 
GeneralBig Problem.... with attachments Pin
dboychuk695-Jan-07 9:25
Memberdboychuk695-Jan-07 9:25 
GeneralRe: Big Problem.... with attachments Pin
yhaker25-May-10 22:34
Memberyhaker25-May-10 22:34 
GeneralHi Nish - Help Needed Pin
aseef25-Sep-06 5:45
Memberaseef25-Sep-06 5:45 
Generaltwice amount mail.. Pin
Daisuke Ota16-Jun-06 20:51
MemberDaisuke Ota16-Jun-06 20:51 
GeneralI have problem with MultiMail 2.o Pin
Malathi Ranjit Singh22-Jan-06 22:15
MemberMalathi Ranjit Singh22-Jan-06 22:15 
GeneralRe: I have problem with MultiMail 2.o Pin
Member 1096674423-Jul-14 8:14
MemberMember 1096674423-Jul-14 8:14 
GeneralRe: I have problem with MultiMail 2.o Pin
Member 1343257027-Sep-17 0:50
MemberMember 1343257027-Sep-17 0:50 
GeneralATL CSMTPConnection - Buggy Pin
jeff66614-Nov-05 3:14
Memberjeff66614-Nov-05 3:14 
GeneralFound a bug with attachment handling Pin
chris_blandford30-Oct-05 3:29
Memberchris_blandford30-Oct-05 3:29 
GeneralNot sending attachments Pin
jbrown0123-Nov-03 15:28
Memberjbrown0123-Nov-03 15:28 
QuestionOld version still availibe? Pin
faj28-Oct-03 2:23
Memberfaj28-Oct-03 2:23 
GeneralEnhancement for next Version Pin
Frank Carius15-Oct-03 1:23
MemberFrank Carius15-Oct-03 1:23 
GeneralMany other uses Pin
Gerard Nicol5-Oct-03 7:21
MemberGerard Nicol5-Oct-03 7:21 
GeneralRe: Many other uses Pin
Nish Nishant5-Oct-03 7:34
sitebuilderNish Nishant5-Oct-03 7:34 
GeneralRe: Many other uses Pin
| Muhammad Waqas Butt |11-Sep-07 21:36
professional| Muhammad Waqas Butt |11-Sep-07 21:36 
GeneralNo support for smtp authentication - intended Pin
Nish Nishant4-Oct-03 9:23
sitebuilderNish Nishant4-Oct-03 9:23 
GeneralPeople who downloaded it before 26th Feb Pin
Nish Nishant26-Feb-02 12:37
sitebuilderNish Nishant26-Feb-02 12:37 
GeneralThanks Pin
[James Pullicino]26-Feb-02 2:58
Member[James Pullicino]26-Feb-02 2:58 
GeneralRe: Thanks Pin
Nish Nishant26-Feb-02 12:36
sitebuilderNish Nishant26-Feb-02 12:36 
GeneralRe: Thanks Pin
[James Pullicino]26-Feb-02 21:14
Member[James Pullicino]26-Feb-02 21:14 
GeneralVolunteers required urgently!!! Pin
Nish Nishant24-Feb-02 0:25
sitebuilderNish Nishant24-Feb-02 0:25 

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