How can the user send email to me from my app ?



  • I have a contact tab in my app in which i want to let user type his/her email, subject and body and whenever they click on submit button the mail should be send to my email address. How can i do that ?


  • Moderators

    @Ahti
    Search for SMTP library for Qt


  • Qt Champions 2016



  • @mrjj

    I actually want to create a forum which has To, From, Subject and body in it and i want user to just type his/her email in the 'From' section and whenever he/she clicks on submit button the mail should get forwarded to me. I don't want him/her to login by giving their email and password i just want them to send me the mail by just mentioning their email address. Is that possible ?


  • Qt Champions 2016

    @Ahti
    Well you own app can allow sending email, however you like.
    BUT the server you are using for sending the emails demands login.
    So your app must login it self for it to send any emails.
    Due to spam, there are very few mail servers that allows sending email
    anonymously these days.



  • @mrjj

    what do you mean by my app should login first ? does that mean i should first login my email account ?


  • Qt Champions 2016

    @Ahti
    To be allowed to send emails via google server you need to be
    authenticated. So yes, your app must "log in" to the google account you
    are sending over.



  • @mrjj

    I don't understand this why i have to login my account ? the user who is using my app sends the email to my email address now if i login my account to the users machine there is no point of it.


  • Moderators

    @Ahti @mrjj probably meant to say that you will need an email service so that users can send an email. And this email service will provide an email gateway. To use this gateway you will need an authentication.



  • @p3c0

    and how can i aquire all this ?


  • Moderators

    Have you registered to any email service ?



  • @p3c0

    I have an account in gmail and yahoo



  • When there is a library that is considered standard I tend to suggest it over some 1-man-wrapper. Not because the latter is bad but it's so much easier to find docs/examples/support when a library is very popular.

    This leads me to libcurl (there are some relatively active C++ bindings like https://github.com/JosephP91/curlcpp but the core C api should be more than enough for what you are trying to do)

    Here you can find an example of sending an email using gmail



  • @VRonin

    Well that is difficult to understand and i don't know how to implement it.



  • @VRonin @p3c0 @mrjj

    Okay guys tell me how can i simply let user to login to his/her email from my app and then let them send email to me ?? I have to get connected to the email server before i let them sign in right ?


  • Moderators

    @Ahti Your users will use their email address only to login to you forum.
    Now that you have email service and a registered user to use that service, your users will use this email user to send email to you.
    You should probably maintain multiple users in case if you have a large userbase.



  • @Ahti said in How can the user send email to me from my app ?:

    Okay guys tell me how can i simply let user to login to his/her email from my app and then let them send email to me ?

    This is even harder as you should know their mail server and sometimes you cannot really access it (for example if they use a private MS exchange server)

    I put here another example with libcurl: https://curl.haxx.se/libcurl/c/smtp-mail.html

    If you think it's not for you then the easy route is using QDesktopServices::openUrl("mailto:youremail@address.com");


  • Moderators

    @Ahti Why not just let the user use their preferred EMail client to send an EMail to you? See http://stackoverflow.com/questions/28674805/open-default-mail-app-from-within-qt-with-some-html
    It is much easier and the user can use his/her EMail client.
    You still can have a form in your app (I guess you meant form not forum?), but then you pass that data via a mailto: URL to the system, which then opens the standard EMail client and fill the data user entered in your form.



  • @jsulm
    Okay why would he has to login from the broswer and then use my app to send email to me ? Can't he simply login to his email account from my app and send mail to me from my app ? And yes i meant form not forum sorry for the mistake. And i used that "QDesktopService..." And it opens up MS outlook.


  • Qt Champions 2016

    Ok. listen. we need to talk about sending emails.

    A program cannot just send email. It need the help of
    a mail server. That is another PC that has a post office program.
    Like GMAIL is. its a mail service.

    So for your program to send mails, you need to send via such server.

    That can happen

    1: You pop outlook via QDesktopService and the mail is sent over whatever server outlook is using.

    2: You send via a google account that your program knows username and password for.
    So before sending email via GOOGLE you will login to this account inside the program.
    This is part of the SMTP protocol.

    3: You use some online mail service where you can send email via some API.

    You could also ask user to login to his mail service but I would never give my password to any unknown program so it's not a good solution and also teaches the users to do stupid things.

    So the part you need to understand is that Sending email demands that the MAIL server knows who u are. So the programs need to supply username and password to the MAil server
    to be allowed to send anything.


  • Moderators

    @Ahti To be sure: when you say "my app" you mean a desktop app? If so then there is no need to log-in from a browser, why do you think so? The user opens that dialog/form in your app, enters needed data (subject, message body) and presses the "Send" button. Then his/her default EMail client is opened where he/she send the EMail from there.



  • @jsulm yes from my desktop app how can i connect to user's email so that he can send email.



  • @mrjj yeah that is what i want, user should login to his mail account from my desktop app and then should sent mail from my desktop app.


  • Moderators

    @Ahti If you want that the user logs in from your app then the user must enter his EMail account data (server address/port, user name, password). That's why I suggested to not to do it this way but just start users EMail client (Outlook, Thunderbird, what ever). This is much easier and the user can use his/her EMail client.
    @mrjj already explained what needs to be done, so it is really not an easy task and overkill in my opinion.



  • Again, maybe I am completely out of line here since I am just a Qt beginner myself, but ur talking about browsers, right?
    So you have some webserver that serves ur app, right?

    If ur server is not able to handle SMTP (mail) then I think we're done talking.

    Look at ur server! Not the app itself...



  • @peteritv said in How can the user send email to me from my app ?:

    Again, maybe I am completely out of line here since I am just a Qt beginner myself, but ur talking about browsers, right?
    So you have some webserver that serves ur app, right?

    If ur server is not able to handle SMTP (mail) then I think we're done talking.

    Look at ur server! Not the app itself...

    I do not believe that sending an e-mail from ur app to you has anything to do with mail suppliers or clients.
    When I put a simple <a with a href to my e-mail account, anyone, no matter what, can send me an e-mail.

    You can even put it in ur apps global stylesheet I guess...


  • Moderators

    @peteritv It is a desktop application as far as I know. See above, I already asked what exactly it is.



  • user should login to his mail account from my desktop app and then should sent mail from my desktop app.

    As jsulm mentioned, this is not a trivial task, the easiest solution is QDesktopServices::openUrl("mailto:youremail@address.com") as VRonin mentioned.
    If you insist on implement smtp functions in your app, the most mature library of c++ I could think of is poco(c is libcurl).

    Following are the example of using gmail by poco

    #include <Poco/Net/MailMessage.h>
    #include <Poco/Net/MailRecipient.h>
    #include <Poco/Net/SMTPClientSession.h>
    #include <Poco/Net/NetException.h>
    #include <Poco/Net/SecureSMTPClientSession.h>
    #include <Poco/Net/InvalidCertificateHandler.h>
    #include <Poco/Net/AcceptCertificateHandler.h>
    #include <Poco/Net/SSLManager.h>
    #include <Poco/Net/SecureStreamSocket.h>
    #include <Poco/Net/MailRecipient.h>
    
    #include <Poco/UnicodeConverter.h>
    
    #include <iomanip>
    #include <iostream>
    #include <string>
    
    int main()
    {
        using namespace Poco::Net;
    
        std::string const host("smtp.gmail.com");
        int const port = 465;
        std::string const sUserName("userEmail@gmail.com");
        std::string const sPassword("whatever");
        std::string const to("MyEmail@gmail.com");
        std::string const from("myUser");
        std::string const subject("new feature suggestion");
        std::string const content("more animations");
        Poco::Net::MailMessage message;
    
        try{
            Poco::SharedPtr<InvalidCertificateHandler> pCert =
                    new AcceptCertificateHandler(false);
            Context::Ptr pContext =
                    new Poco::Net::Context(Context::CLIENT_USE, "", "",
                                           "", Context::VERIFY_NONE);
            SSLManager::instance().initializeClient(0, pCert, pContext);
    
            SecureStreamSocket pSSLSocket(pContext);
            pSSLSocket.connect(SocketAddress(host, port));
            SecureSMTPClientSession secure(pSSLSocket);
    
            secure.login();
            bool const tlsStarted = secure.startTLS(pContext);
            std::cout<<"tls can start : "<<std::boolalpha<<tlsStarted<<std::endl;
            secure.login(SMTPClientSession::AUTH_LOGIN, sUserName, sPassword);
    
            message.setSender(from);
            message.addRecipient(MailRecipient(MailRecipient::PRIMARY_RECIPIENT, to));
            message.setSubject(subject);
            message.setContentType("text/plain; charset=UTF-8");
            message.setContent(content, MailMessage::ENCODING_8BIT);
    
            std::cout<<"send message"<<std::endl;
            secure.sendMessage(message);
            std::cout<<"close sender"<<std::endl;
            secure.close();
        }catch(SMTPException &e){
            std::cerr << e.code() << std::endl;
            std::cerr << e.message() << std::endl;
            std::cerr << e.what() << std::endl;
            std::cerr << e.displayText().c_str() << std::endl;
        }catch (NetException &e){
            std::cerr << e.code() << std::endl;
            std::cerr << e.message() << std::endl;
            std::cerr << e.what() << std::endl;
            std::cerr << e.displayText().c_str() << std::endl;
        }catch(std::exception const &ex){
            std::cerr<<ex.what()<<std::endl;
        }
    }
    

    Not every email server works with this example(I guess in most cases what you need to do is adjust the host and port), if you want to support different servers(gmail, hotmail etc), you will need to try them out one by one.

    If you do not want to force the users enter their user name and password all of the times, you can save their input by QSettings(better ask the user they want to store their passwords and user name before they do that, and allowed them to remove it later).

    However, I will prefer this simple SMTP class which only depends on Qt5, because dependency problems of c++ could be quite nasty to solve.


  • Moderators

    To be honest if I would be a user of such an application I would NEVER enter my login data for my EMail account! I only trust my EMail client. An application asking me for my EMail login data would be uninstalled immediately.



  • @mrjj @peteritv @tham @jsulm

    ok guys i used the desktopservice::openurl...mailto.. but its opening outlook what if user doesn't have outlook ? why can't i simply open the browser and let him login to his email server and when he/she is logged in i should go directly to compose email and then in 'to' section there should be my emailaddress . how to do that ?


  • Moderators

    @Ahti desktopservice::openurl will open the EMail client the user configured. In your case it looks like this is Outlook, for other users it can be something else (on my Linux machine it would open Thunderbird), no issue here.
    Regarding your last question: not all users use web access to their EMail accounts and I don't think there is a standard way to pass all the data for the EMail to such web based EMail clients.



  • @Ahti do you have your own public server? If so, then perhaps the most easy way would be to code a simple http API that your app (with somekind of authentication obviously) can do a simple http POST to, and that thing then sends the e-mail to you.


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