By default, you need to enable ” Allowing less secure apps” in Gmail/G Suite, then you can retrieve email with user/password IMAP4 authentication.
However Google will disable traditional user authentication in the future, switching to Google OAuth is strongly recommended now.
Sections:
Before you can use the following sample codes, you should download the EAGetMail Installer and install it on your machine at first. Full sample projects are included in this installer.
To better demonstrate how to retrieve email and parse email, let’s create a Delphi Standard EXE project at first, then add a TButton on the Form, double-click this button. It is like this:
To use EAGetMail ActiveX Object in your Delphi project, the first step is “Add Unit file of EAGetMail to your project”. Please go to
C:\Program Files\EAGetMail\Include\delphi
or
C:\Program Files (x86)\EAGetMail\Include\delphi
folder,
find EAGetMailObjLib_TLB.pas
, and then copy this file to your project folder.
// include EAGetMailObjLib_TLB unit to your Delphi Project
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, EAGetMailObjLib_TLB, StdCtrls;
Then you can start to use it in your Delphi Project.
You can also create EAGetMailObjLib_TLB.pas manually by Delphi like this:
Delphi 7 or eariler version
First of all, create a standard delphi project: select menu Project
-> Import Type Library
, checked EAGetMail ActiveX Object
and click Create Unit
.
Then include EAGetMailObjLib_TLB
in your project.
Delphi XE or later version
First of all, create a standard delphi project: select menu Component
-> Import component...
-> Import a type library
-> checked EAGetMail ActiveX Object
,
have Generate Component Wrapper
checked and click “Create Unit”. Then include EAGetMailObjLib_TLB
in your project.
Normal OAuth requires user input user/password in Web Browser. Obviously, it is not suitable for background service. In this case, you should use google service account to access G Suite email service without user interaction. Service account only works for G Suite user, it doesn’t work for personal Gmail account.
To use “G Suite Service Account OAuth” in your application, you should create a project in Google Developers Console at first.
Important
You can use any google user to create service account, it doesn’t require service account owner is a user in G Suite. But G Suite administrator must authorize service account in G Suite Admin Console to access user mailbox.
Open Google Developer Console, create a new project by https://console.developers.google.com/projectcreate.
After you created the project, select it from projects list as current project.
Click "Credentials"
-> "Manage service accounts"
Click "CREATE SERVICE ACCOUNT"
Input a name for your service account, click "CREATE"
In "Service account permissions"
, select "Project"
-> "Owner"
as role
In "Grant users access to this service account"
, keep everything default and click "DONE"
After service account is created, you should enable "Domain-wide delegation"
and create service key pair
to access G Suite user mailbox.
Go back to your service account, click "Edit"
-> "SHOW DOMAIN-WIDE DELEGATION"
,
check "Enable G Suite Domain-wide Delegation"
, input a name for product oauth consent, click "Save"
.
Go back to your service account again, click "Create Key"
, you can select "p12"
or "json"
key type,
both can work well, then you will get a file which contains private key, save the file to local disk.
Now you have created service account with key pair successfully. You can use created private key in your
codes to request "access token"
impersonating a user in G Suite.
To access user data in G Suite, you must get authorization from G Suite administrator.
You should go to service accounts list, click "View Client ID"
like this:
Then copy your “Client ID” and service account email address, forward it to G Suite administrator for authorization.
Enable Gmail API in "Library"
-> Search "Gmail"
, then click "Gmail API"
and enable it.
If you use Gmail API protocol to send email, you should enable this API, if you use SMTP protocol, you don’t have to enable it.
To use service account to access user mailbox in G Suite, G Suite Administrator should authorize specified service account at first.
Important
Important Notice: You can use any google user to create service account, it doesn’t require service account owner is a user in G Suite. But G Suite administrator must authorize service account in G Suite Admin Console to access user mailbox.
G Suite Administrator should open admin.google.com, go to Admin Console, click "Security"
> API Control
;
Click Add new and enter your service account client ID.
Enter the client ID
of the service account or OAuth2 client ID of the app.
In OAuth Scopes, add each scope that the application can access (should be appropriately narrow).
and input https://mail.google.com/
, email
, profile
in One or More API Scopes, click "Authorize"
.
After G Suite administrator authorized service account, you can use it to access any users mailbox in G Suite domain.
Because HttpWebRequest is used to get access token from web service.
If you’re using legacy .NET framework (.NET 2.0 - .NET 3.5 and .NET 4.0 - 4.6.1),
you need to enable Strong Encryption Algorithms
to request access token:
Put the following content to a file named NetStrongEncrypt.reg
, right-click this file -> Merge
-> Yes
.
You can also download it from https://www.emailarchitect.net/webapp/download/NetStrongEncrypt.zip.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v2.0.50727]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v2.0.50727]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001
You don’t have to request access token
every time. By default,
access token
expiration time is 3600 seconds, you can use the access token
repeatedly before it is expired.
Important
You should create your client id
and client secret
, do not use the client id
from example codes in production environment,
it is used for test purpose. If you got "This app isn't verified"
information, please click "Advanced"
-> Go to ...
for test.
program Project1;
{$APPTYPE CONSOLE}
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, ActiveX, MSXML2_TLB, EAGetMailObjLib_TLB;
const
MailServerPop3 = 0;
MailServerImap4 = 1;
MailServerEWS = 2;
MailServerDAV = 3;
MailServerMsGraph = 4;
// Auth type
MailServerAuthLogin = 0;
MailServerAuthCRAM5 = 1;
MailServerAuthNTLM = 2;
MailServerAuthXOAUTH2 = 3;
CRYPT_MACHINE_KEYSET = 32;
CRYPT_USER_KEYSET = 4096;
CERT_SYSTEM_STORE_CURRENT_USER = 65536;
CERT_SYSTEM_STORE_LOCAL_MACHINE = 131072;
// GetMailInfosParam Flags
GetMailInfos_All = 1;
GetMailInfos_NewOnly = 2;
GetMailInfos_ReadOnly = 4;
GetMailInfos_SeqRange = 8;
GetMailInfos_UIDRange = 16;
GetMailInfos_PR_ENTRYID = 32;
GetMailInfos_DateRange = 64;
GetMailInfos_OrderByDateTime = 128;
function RequestAccessToken(requestData: WideString): WideString;
var
httpRequest: TServerXMLHTTP;
oauthParser: TOAuthResponseParser;
fullRequest: OleVariant;
status: integer;
responseText: WideString;
accessToken: WideString;
begin
result := '';
httpRequest := TServerXMLHTTP.Create(nil);
fullRequest := 'grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Ajwt-bearer&assertion=';
fullRequest := fullRequest + requestData;
httpRequest.setOption(2, 13056);
httpRequest.open('POST', 'https://oauth2.googleapis.com/token', true);
httpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
httpRequest.send(fullRequest);
while( httpRequest.readyState <> 4 ) do
begin
try
httpRequest.waitForResponse(1);
except
writeln('Server response timeout (access token).');
exit;
end;
end;
status := httpRequest.status;
responseText := httpRequest.responseText;
if (status < 200) or (status >= 300) then
begin
writeln('Failed to get access token from server.' + responseText);
exit;
end;
oauthParser := TOAuthResponseParser.Create(nil);
oauthParser.Load(responseText);
accessToken := oauthParser.AccessToken;
if accessToken = '' then
begin
writeln('Failed to parse access token from server response.');
exit;
end;
result := accessToken;
end;
function GenerateRequestData(gsuiteUser: WideString): WideString;
const
// service account email address
serviceAccount: WideString = 'xxxx@xxxx.iam.gserviceaccount.com';
scope: WideString = 'https://mail.google.com/';
aud: WideString = 'https://oauth2.googleapis.com/token';
var
jwt: TSimpleJsonParser;
cert: TCertificate;
pfxPath: WideString;
header: WideString;
playload: WideString;
signature: WideString;
iat, exp: integer;
begin
result := '';
SetThreadLocale(GetSystemDefaultLCID());
jwt := TSimpleJsonParser.Create(nil);
header := jwt.JwtBase64UrlEncode('{"alg":"RS256","typ":"JWT"}');
// token request timestamp
iat := jwt.GetCurrentIAT();
// token expiration time
exp := iat + 3600;
playload := '{';
playload := playload + '"iss":"' + serviceAccount + '",';
playload := playload + '"scope":"' + scope + '",';
playload := playload + '"aud":"' + aud + '",';
playload := playload + '"exp":' + IntToStr(exp) + ',';
playload := playload + '"iat":' + IntToStr(iat) + ',';
playload := playload + '"sub":"' + gsuiteUser + '"';
playload := playload + '}';
playload := jwt.JwtBase64UrlEncode(playload);
cert := TCertificate.Create(nil);
// load service account certificate to sign request data
pfxPath := 'D:\MyData\GSuite\outh-77aec4d192ec.p12';
cert.LoadFromFile(pfxPath, 'notasecret', CRYPT_USER_KEYSET);
signature := jwt.SignRs256(cert.DefaultInterface, header + '.' + playload);
if signature = '' then
begin
writeln('Failed to sign request data!');
exit;
end;
result := header + '.' + playload + '.' + signature;
end;
procedure RetrieveEmail();
var
gsuiteUser, accessToken: WideString;
oServer: TMailServer;
oClient: TMailClient;
oTools: TTools;
oMail: IMail;
infos: IMailInfoCollection;
oInfo: IMailInfo;
localInbox, fileName: WideString;
i: Integer;
begin
try
gsuiteUser := 'user@gsuitedomain';
// request access token with service account
// gsuiteUser is the full email address of the user in GSuite, for example: user@gsuitedomain
accessToken := RequestAccessToken(GenerateRequestData(gsuiteUser));
if accessToken = '' then
exit;
// set current thread code page to system default code page.
SetThreadLocale(GetSystemDefaultLCID());
oTools := TTools.Create(nil);
// Create a folder named "inbox" under
// current directory to store the email files
localInbox := GetCurrentDir() + '\inbox';
oTools.CreateFolder(localInbox);
oServer := TMailServer.Create(nil);
// Gmail IMAP Server
oServer.Server := 'imap.gmail.com';
// Use OAUTH 2.0
oServer.AuthType := MailServerAuthXOAUTH2;
oServer.User := gsuiteUser;
// Use access token as password
oServer.Password := accesstoken;
// Use IMAP Protocol
oServer.Protocol := MailServerImap4;
// Enable SSL Connection
oServer.SSLConnection := true;
// Set IMAP SSL Port
oServer.Port := 993;
oClient := TMailClient.Create(nil);
oClient.LicenseCode := 'TryIt';
writeln('Connecting ' + oServer.Server + ' ...');
oClient.Connect1(oServer.DefaultInterface);
writeln('Connected!');
// Get new email only, if you want to get all emails, please remove this line
oClient.GetMailInfosParam.GetMailInfosOptions := GetMailInfos_NewOnly;
infos := oClient.GetMailInfoList();
writeln(Format('Total %d email(s)', [infos.Count]));
for i := 0 to infos.Count - 1 do
begin
oInfo := infos.Item[i];
writeln(Format('Index: %d; Size: %d; UIDL: ' + oInfo.UIDL,
[oInfo.Index, oInfo.Size]));
// Generate a random file name by current local datetime,
// You can use your method to generate the filename if you do not like it
fileName := localInbox + '\' + oTools.GenFileName(i) + '.eml';
// Receive email from IMAP server
oMail := oClient.GetMail(oInfo);
writeln('From: ' + oMail.From.Address + #13#10 +
'Subject: ' + oMail.Subject);
// Save email to local disk
oMail.SaveAs(fileName, true);
// Mark email as read to prevent retrieving this email again.
oClient.MarkAsRead(oInfo, true);
// If you want to delete current email, please use Delete method instead of MarkAsRead
// oClient.Delete(oInfo);
end;
// Quit and expunge emails marked as deleted from IMAP server
oClient.Quit;
except
on ep:Exception do
writeln('Error: ' + ep.Message);
end;
end;
begin
CoInitialize(nil);
writeln('+------------------------------------------------------------------+');
writeln(' Sign in with Google OAuth');
writeln(' If you got "This app is not verified" information in Web Browser, ');
writeln(' click "Advanced" -> Go to ... to continue test.');
writeln('+------------------------------------------------------------------+');
writeln('');
writeln('Press ENTER key to sign in...');
readln;
RetrieveEmail();
writeln('Press ENTER key to quit...');
readln;
end.
TLS is the successor of SSL, more and more SMTP servers require TLS 1.2
encryption now.
If your operating system is Windows XP/Vista/Windows 7/Windows 2003/2008/2008 R2/2012/2012 R2
, you need to
enable TLS 1.2 protocol in your operating system like this:
Enable TLS 1.2 on Windows XP/Vista/7/10/Windows 2008/2008 R2/2012
Appendix
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