SMTP Mail Sender

smtpsendSMTP Mail Sender is an application that allows you to send messages through an SMTP server. It lets you send messages if you do not have a mail application installed, or need to send from an account that is only used for sending messages without worrying about responses. It also runs from a USB thumb drive, so you can send emails from anywhere you have access to a computer with Internet access.

  • Graphical user interface (GUI) instead of the run of the mill command line applications. UI allows customization by showing/hiding fields as necessary.
  • If you need a true command line application that does not display a user interface, I highly recommend Blat.
  • Built in address book saves you time typing email addresses, guesses and auto-completes addresses already in the address book
  • Send messages using a SMTP server from any Internet connected computer from a thumb drive
  • Supports attaching an unlimited amount of files to the message before sending
  • Sends plain text messages to minimize bandwidth used for processing the messages as they travel across the Internet.
  • Includes language support for English, French, Italian and Spanish
  • Send messages automatically from a script using command line parameters. A GUI dialog will still pop up when automatically sending the message.

Want to use SMTP Mail Sender in a different language? Check the comments below to see if someone has already provided a translation. If not, and you want to help translate to your local language, provide the translation via this template for others to use in the comments section. Have a few moments to spare? Please rate SMTP Mail Sender at the SnapFiles website!

SMTP Mail Sender requires the Microsoft .NET 2.0 Framework.
Supported/Tested Operating Systems: Windows® XP SP3, Windows 7 Home/Pro 64bit, Support on Windows® Server is limited to GUI mode, it cannot be run in Service Mode at this time.

Lost and confused? Check the frequently asked questions page.

What do you think about SMTP Mail Sender? Rate it!
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Change Log

46 thoughts on “SMTP Mail Sender

  1. AvatarAlex

    Hey Joey,

    Pretty cool utility. It would be very useful to see the negotiation process while the software is talking to the SMTP server and any errors generated from sending. What do you think about adding some functionality like that?


    1. Joey HazlettJoey Hazlett Post author

      Hi Alex. Thank you for the suggestion. If you enable the logging feature in the options for the application, you can watch the output to the log file to see the steps happening in the process. I’m not sure if there needs to be a dedicated function for that built into the application. After a quick web search, it looks like you should be able to use PowerShell to “tail” the smtpsend.log file from SMTP Mail Sender.

  2. AvatarGeoffrey Mosini

    Hi !
    It happens I can’t launch your utility from my computers (windows 7 pro or windows 10 pro).
    It just displays “The program has stopped working”.
    I did a check to see if .Net dependencies are missing, but it seems fine…
    Any idea ?

  3. AvatarZdenko

    Absolutely excellent software!
    Simple, only one exe, no install – wonderful.
    Had problems with not working powershell script Send-MailMessage in windows 10, but this one successfully send a mail at the first attempt. I’m impressed!

    Now the main problem:
    Windows 10 x64, 1803, no mail client installed, document scanner attached. There is no mail account, just a valid SMTP server on LAN with proper sender email address.
    When attempted to send scanned document by email, “no mail client installed. If one is already installed, create an association in the Default programs control panel”
    Can not create this association, as SMTPmailsender is not listed there, and there is no possibility to browse/search one.
    Is there any way to set SMTPmailsender as a default mail program in windows 10?

    Best Regards,

  4. AvatarPierce Desjarlais

    This is probably a total fringe case, but would it be possible to have a switch for the program to send as an HTML(-html or -BodyAsHtml or something?), even if the editor doesn’t support rich text and HTML? One service I use assumes that the body of a non-HTML email is itself an attachment instead of the body of the original message. Its not a significant issue but would be helpful.

    1. Joey HazlettJoey Hazlett Post author

      Unfortunately, it’s not currently possible. I’ve looked into this to try implementation of HTML email per the requests of other users. The email library that is part of the .NET framework does not seem to support HTML emails, even if you define the content-type header as text/html. The problem is that just defining the email as html does not work, you have to actually MIME encode the entire message. 🙁 Supporting HTML email would require using a completely different library, possibly requiring a complete rewrite of the application.

  5. AvatarPierce Desjarlais

    Would it be possible to have a command line switch to specify the address book file being used?

    1. Joey HazlettJoey Hazlett Post author

      Hi Pierce! Yes this sounds like a useful addition. I will add it to my request/bug tracking. Thanks for the suggestion.

    2. Joey HazlettJoey Hazlett Post author


      Version now supports the -addbook “file” parameter to allow you to specify which address book file to use. See the readme file for information.

  6. AvatarYunlai

    Dear sir,
    Great software. I have one doubt though.
    I tried Gmail and Yahoo to send mail via port 587 and succeed. However, I failed if I use port 25(ssl not ticked) or 465(ssl ticked).

  7. AvatarYunlai

    Dear sir,
    Great software!
    But I have one doubt. I tried both Gmail and Yahoo to send mail via port 587 and succeed. However, I failed if I use port 25(without tick SSL) and port 465(tick SSL).
    It seems like only port 587 works.
    Yunlai Feng

    1. Joey HazlettJoey Hazlett Post author

      Hello Yunlai,

      You are correct in your findings. Gmail and Yahoo both only support port 587 for submitting email from individual clients. Port 25 is generally only allowed to accept mail from other mail servers. Port 465 at those services requires full protocol encryption, but SMTP Mail Sender only supports TLS encryption. I should update the application to label it as “TLS” instead of “SSL” in the configuration settings to avoid this confusion in the future.

      1. AvatarQual

        Quote: I should update the application to label it as “TLS” instead of “SSL”

        Indeed very confusing.
        Label still not updated to TLS on April 2th 2018 🙁
        HTML support would also be appreciated.
        Thank you for this useful mailsender

        1. Joey HazlettJoey Hazlett Post author

          Hi Qual,

          Thanks for the reminder to release the newest version. The change was made in the code, but I never released the build to the wild. Version should now read TLS instead of SSL. It also supports specifying a non-standard address book file location using the -addbook “file” parameter. See the readme file for information.

  8. AvatarColin Foster

    When the “Keep open after sending” box is ticked the first message I send goes fine, but subsequent messages don’t. If I then close and reopen the app the first message goes fine but once again subsequent ones don’t. This is 100% repeatable here.

    1. Joey HazlettJoey Hazlett Post author

      Hi Colin,

      Thank you for the report. I can confirm that it is doing it to me as well. I will look into this when I get a few moments and see if I can figure out what is causing the problem.

      1. Joey HazlettJoey Hazlett Post author


        I’ve posted a new version of SMTP Mail Sender that fixes the problem you were experiencing. Download the latest version from this page for the fix.

          1. Joey HazlettJoey Hazlett Post author

            Hi Milburn,

            I am not sure what you are asking. Do you need help using SMTP Mail Sender, or do you need help learning the simple mail transport protocol?

  9. AvatarDaniele

    HI, great software! I need to know if is possible to add all the email address in the Address Book directly without selecting one by one. Thanks!

    1. Joey HazlettJoey Hazlett Post author

      Hi Daniele,

      Once you’ve added the first name to the address book so the file is created, you can edit the file with a simple text editor like Notepad. Just open the addbook.conf file with notepad and you’ll see the format. Basically it’s just:

      Name <email@address>
      Name 2 <email2@address>

      You can add as many as you want there, and they’ll be loaded the next time you launch SMTP Mail Sender.

      1. AvatarDaniele

        This was my first reply (via email): “Probably, due to my bad english, I didn’t explain well what I need. I had 100 email address in my address book, added from outlook, it was very easy to do. I’d like to know if I can add all these address as recipient when I compose a new message without insert one by one. Something like select recipients from address book. Thanks in advance”
        And now, after the update I can say ALMOST PERFECT!
        Only two things: the download links show version but the correct one is and I’ve a little problem with the gui, the envelope icon and the “Settings” button are cutted, while the new options is perfect.
        I’ll send you a screenshot via email.
        Thanks a lot

  10. AvatarJohan Lijffijt


    Is the smtpsend log the only log? I get the following if i try office365 or gmail

    ************* gmail **********************
    3/29/2017 11:25:58 AM Enabling SSL connection
    3/29/2017 11:25:58 AM Connecting to
    3/29/2017 11:25:58 AM Sending credentials –********
    3/29/2017 11:25:58 AM Sending message to
    3/29/2017 11:26:08 AM Syntax error, command unrecognized. The server response was: << — And then the mesaage stops. What is the response ??
    ********** office 365 *********************
    3/29/2017 11:29:20 AM Enabling SSL connection
    3/29/2017 11:29:20 AM Connecting to
    3/29/2017 11:29:20 AM Sending credentials – xx@xx.xx:********
    3/29/2017 11:29:20 AM Sending message to xx@xx.xx
    3/29/2017 11:29:20 AM Failure sending mail. << — Nothing is said what kind of failure. What is the failure ?

    1. Joey HazlettJoey Hazlett Post author

      Hi Johan,

      There aren’t any more log files, this is the only one. Those error messages you are receiving are coming directly from the mail server. The application just writes the error message to the file along with the time stamp. For Gmail, please try port 587 instead of 465. Gmail expects the full transaction to be encrypted on port 465, but it uses a feature called STARTTLS on 587 to accept email. SMTPMailSender uses some built-in .NET functions that do not fully support encryption of the entire connection, so each command is encrypted instead of sending plain text over a completely secure tunnel. Due to that, Gmail is expecting plain text and receiving an encrypted command.

      I do not have any experience with Office 365. The first thing I’d try is to just disable SSL. I agree it’s hard to troubleshoot further when the remote server gives such a vague error, but there’s not much more SMTPMailSender can do other than report what it was told happened. I’m just speculating here, but is it possible that you’d need to enable SMTP access for your O365 account? Some webmail services do not allow submission of messages from remote hosts without prior authorization, to combat spamming.

      Hopefully my thoughts will help you get SMTPMailSender working in your environment.

  11. AvatarGeoff

    I can use it fine with my ISP smtp but doesn’t seem compatible with Gmail. I’ve tried it with 3 gmail accounts and it doesn’t send, gives error saying “syntax error: unrecoqnized command” in the log.

    1. AvatarGeoff

      I’ve been using port 465 which Google says to use with SSL. So instead I gave 587 a try, and it worked. I’ve tried 465 using separate ISPs too. Perhaps its being blocked. Thanks for making such a useful tool, much appreciated.

  12. AvatarJude

    This is a great software. Please when will you include the HTML formatted body functionality?

    1. Joey HazlettJoey Hazlett Post author


      There is no immediate plan to include HTML formatted body functionality. It is a simple tool for Windows systems that was designed to send one-off emails, mostly for reporting when processes complete. If you need capability such as HTML formatting, I suggest moving up to a standard email client like Mozilla Thunderbird. There are portable versions available, which will let you run it from a thumb drive, replicating most of the features in SMTP Mail Sender and then some.


  13. AvatarJDough

    Hey thank you very much!
    Hal9000 has a great suggestion.

    I’d like to add, can we use encryption inside or outside this fine app so we can sidestep any looking on my gmail?
    IF so how?

    Again thank you muchly!

    1. Joey HazlettJoey Hazlett Post author


      In regards to Hal9000’s suggestion, there are CC and BCC fields available for use in SMTP Mail Sender, and have been since version If you do not see these in your version, you may need to download the latest version from this page.

      As for encryption, you can enable SSL, but that only encrypts the traffic between your computer and the Gmail servers. Once it has completed that step, you have no further control over who does or does not see the message, that’s under the control of the email provider.

  14. AvatarJason

    Hi All

    Was just wondering if i can call this app through a batch file to populate some fields and send

  15. AvatarGordie Brown

    What would really round it off would be a return code confirming a send or escape.

  16. AvatarOle

    Nice little App, if only it worked for me…

    Can someone tell me, why it won’t send my emails?! I’ve tried all sorts of servers, from Hotmail, Gmail, etc, and the Emails never arrive… Does it connect to a certain IP, that my IP Blocker might be Blocking?!

    1. Joey HazlettJoey Hazlett Post author


      If you are using Gmail, you will need to configure the application to use Google’s mail servers. There are instructions available on Google’s site on how to do this.

      Your ISP may block outgoing mail on SMTP port 25. If that is the case, you will want to configure it to use port 465 and enable SSL. I’ve never tested with Hotmail, but I know that it will work with Gmail and Yahoo, as I’ve used both of those before (and still do).


  17. AvatarMike

    It would be really cool to add HTML formatted body functionality

  18. AvatarJosue Aguilar

    Thanks Joey for all this free software your are offering.Here goes the Spanish translation

    From= De
    To= Para
    Subject= Asunto
    Message Body= Mensaje
    Attachment(s)= Adjunto
    Add= Agregar, anexo
    Open Text File=Abrir Archivo de Texto
    Insert Text File= Insertar Archivo de Texto
    Settings= Configuraciones
    Keep open after sending= Mantener abierto despues de enviar
    Send= Enviar
    Send a message= Enviar un Mensaje
    Server= Servidor
    Port= Puerto
    Secure Connection (SSL)= Conección Segura (SSL)
    Server requires authentication= Servidor Requiere autenticación
    Username= Nombre de Usuario
    Password= Clave
    Composition Font= Fuente
    About= Sobre
    Cancel= Cancelar
    OK= Ok
    Add new entry= Añadir nueva entrada
    Name= Nombre
    Address= Dirección
    Delete= Borrar
    Save= Guardar
    Address Book= Libro de Direcciones

  19. AvatarJorge Rossiter

    Thanks for the excellent software. Here goes the Portuguese Brazilian translation:

    Message Body:=Mensagem
    Open Text File=Abrir Arquivo de Texto
    Insert Text File=Inserir Arquivo de Texto
    Keep open after sending=Manter aberto depois do envio
    Send a message=Enviar uma mensagem
    Secure Connection (SSL)=Conexão Segura (SSL)
    Server requires authentication=Servidor requer autenticação
    Composition Font:=Fonte:
    Add new entry=Adicionar nova entrada
    Address Book=Catálogo de Endereços

  20. Avatargemmy

    Thanks a lot for the freeware that you offered and your effort given.

    The following translation is Chinese simplified:

    Message Body=内容
    Open Text File=打开文本文件
    Insert Text File=插入文本文件
    Keep open after sending=发送后保持运行
    Send a message=发送信息
    Secure Connection (SSL)=安全连接(SSL)
    Server requires authentication=服务器需要验证
    Composition Font=字体
    Add new entry=添加新项
    Address Book=通讯录

  21. AvatarHedi

    Thanks Joey for all the free software your are offering.
    I enjoy using StoreURL and Networx every day. I am delighted.
    I hope helping you with this French translation of the SMTP Mail sender.
    I have a 10 years computers and telecoms engineering background as well as being a Quality Auditor and ISO 9001 Certifier.
    Don’t hesitate contacting me If I could be in any help for your future projects: (Auditing, Beta Testing, Analysis, etc…).

    Best Regards

    Message Body=Message
    Attachment(s)=Pièce(s) Jointe(s)
    Open Text File=Ouvrir Fichier Texte
    Insert Text File=Insérer Fichier Texte
    Keep open after sending=Laisser ouvert après envoi
    Send a message=Envoyer Message
    Secure Connection (SSL)=Connection Sécurisée (SSL)
    Server requires authentication=Le Serveur Requière Authentification
    Username=Nom d’Utilisateur
    Password=Mot de Passe
    Composition Font=Police de Composition
    About=A Propos
    Add new entry=Ajouter nouvelle Entrée
    Address Book= Répertoire d’Adresses


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