This code is deprecated and should no longer be used. It requires a complete rewrite against the gmail api https://developers.google.com/gmail/api . Given the availability of https://www.mapi4gmail.com/ and https://www.affixa.com/ it doesn't make sense for us to do so. The code was expected to stop working for new users on june 15th 2020 but Google delayed that due to COVID-19. https://gsuiteupdates.googleblog.com/2019/12/less-secure-apps-oauth-google-username-password-incorrect.html Tvhgooglemapi and gmaildrafter are a pair of tools that can be used to make the following menu entries work with google mail without having to install a complete mailclient like Thunderbird or Outlook. File->Send To->Mail recipient (as attachment) (in MS Word) File->Send->Document as email (and the related entries in LibreOffice and OpenOffice.org) File->Attach to email (in Acrobat Reader) All other windows applications that use Simple MAPI MAPISendMail might work but have not been tested. When installing tvhgooglemapi gmaildrafter is automatically installed. tvhgooglemapi is the part that integrates with windows and gmaildrafter actually uploads the mail as a draft and opens the draft in your default webbrowser. In theory gmaildrafter could also be used to implement other 'send mail' functions. In addition to that you also need a Java Runtime (at least version 1.6) You can get one here: http://www.oracle.com/technetwork/java/index.html Imap is used to upload the mail, so you need to enable IMAP in your gmail settings and imaps trafic has to be allowed on the network (port 993.) If you're using multiple accounts with gmail the primary logged in account in your browser must be the one you want to use for this application or it won't work. The application can't determine the signature of the user. If you want to include a signature in the mails created by this application you can put it in the file %USERPROFILE%\.gmaildrafter\signatures\username@domain.com.html When installing the required registry keys are automatically set. In case you ever need to modify them (ie after temporarily changing the default mailclient) you need the following settings: [HKEY_LOCAL_MACHINE\SOFTWARE\Clients\Mail\tvhgooglemapi] @="tvhgooglemapi" "DLLPath"="C:\\Program Files (x86)\\tvhgooglemapi\\tvhgooglemapi.dll" [HKEY_CURRENT_USER\Software\Clients\Mail] @="tvhgooglemapi" If a user chooses to store his login credentials these are stored in %USERPROFILE%\.gmaildrafter . While the password is hidden an average developer will be able to decode it, so keep these files private and do not store the password on a computer you don't trust. If you want to automatically attach a signature to your email you can put a file in %USERPROFILE%\.gmaildrafter\signatures\yourusername@yourdomainname.com.html which contains the text in html. The folder signatures will not be there. You have to create it yourself. Then you need to create a html file in that folder that has as name: matching your email address followed by .html. If you never created a html file there's a quick writeup here: http://csis.pace.edu/~wolf/HTML/htmlnotepad.htm There are many more examples if you google for 'create html file'. Note that if you use images they will have to be online (img src="http:///... it won't work if the image is on your local harddrive. One detail: The file needs to contain at least one html closing tag. () If this is not the case the program will assume it is plain text and escape all html characters, as a result the entire signature would be on a single line in the final mail. If you want to compile the dll yourself you'll need Microsoft Visual C++ 2010 Express Edition (http://www.microsoft.com/visualstudio/en-us/products/2010-editions/visual-cpp-express) and boost (http://www.boost.org/). (Other compilers might work but have not been tested.) The Java application uses Apache Commons CLI (http://commons.apache.org/cli/), Apache Commons IO (http://commons.apache.org/io/) and Apache Commons Lang (http://commons.apache.org/lang/) in addition to the java-gmail-imap implementation of JavaMail (https://code.google.com/p/java-gmail-imap/). The sources include a Netbeans Project, but another ide should do just fine. The installer is made with innosetup. If you have a problem with the application please report them at https://github.com/jankeirse/tvhgooglemapi/issues If your problem refers to gmail exit code 1 please create a file in c:\windows\temp\debuggmaildrafter.txt , try to send a mail again and when there is a popup 'Going to execute the last command in c:\windows\temp\debuggmaildrafter.txt' before confirming this popup, open the file c:\windows\temp\debuggmaildrafter.txt and run the last line in dos (Start->execute->cmd.exe) It will most likely provide valueable information. By default tvhgooglemapi will open the draft in a new browser tab/window. If you are using Google Chrome there is an extension that makes sure that only one tab for gmail is open (and also only one for google calendar,...) Using this extension will cause the draft to be opened in the tab where you had gmail open, some people may find that desireable. You can find it here: https://chrome.google.com/webstore/detail/tab-fixer-for-google-apps/cplbkecindmpapmnffepmnbiogpllcni/details It's support page is here: https://code.google.com/p/google-apps-tab-fixer/wiki/FAQ