SendEmail with Indy components

I try to send an email, but I have a problem, however, I found this code on the web:

Uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, IdMessage, IdTCPConnection, IdTCPClient,
IdMessageClient, IdSMTP, IdBaseComponent, IdComponent, IdIOHandler,
IdExplicitTLSClientServerBase, IdSMTPBase

procedure SendSimpleMail;
var
Msg: TIdMessage;
DestAddr: TIdEmailAddressItem;
begin
Msg := TIdMessage.Create(Self); //error here
Msg.From.Text := 'name';
Msg.From.Address := 'username@gmail.com';
Msg.Subject := 'Test';

DestAddr := Msg.Recipients.Add;
DestAddr.Text := 'name';
DestAddr.Address := 'username@yahoo.com';
Msg.Body.Add('simple test mail.');

tIdSMTP.Host := 'smtp.gmail.com';
tIdSMTP.Port := 25;
tIdSMTP.AuthenticationType := atLogin; //error here (2 error)
tIdSMTP.Username := 'username@gmail.com';
tIdSMTP.Password := 'password';
tIdSMTP.Connect;
tIdSMTP.Authenticate;
tIdSMTP.Send(Msg);
tIdSMTP.Disconnect;
end;

But however, I noted many mistakes and I am missing a component of Indy. Compiler errors:

[DCC Error] Unit1.pas(36): E2003 Undeclared identifier: 'Self'
[DCC Error] Unit1.pas(46): E2233 Property 'Host' inaccessible here
[DCC Error] Unit1.pas(47): E2233 Property 'Port' inaccessible here
[DCC Error] Unit1.pas(48): E2003 Undeclared identifier: 'AuthenticationType'
[DCC Error] Unit1.pas(48): E2003 Undeclared identifier: 'atLogin'
[DCC Error] Unit1.pas(49): E2233 Property 'Username' inaccessible here
[DCC Error] Unit1.pas(50): E2233 Property 'Password' inaccessible here
[DCC Error] Unit1.pas(51): E2076 This form of method call only allowed for class methods
[DCC Error] Unit1.pas(52): E2076 This form of method call only allowed for class methods
[DCC Error] Unit1.pas(53): E2076 This form of method call only allowed for class methods
[DCC Error] Unit1.pas(54): E2076 This form of method call only allowed for class methods
[DCC Error] Project1.dpr(5): F2063 Could not compile used unit 'Unit1.pas'

Thanks for the help in advance

Solution

The code from your question is written for Indy 9 and from your compiler error seems you're using Indy 10. To your compiler errors:

Undeclared identifier: Self - the Self is the pointer to the class instance itself and since you didn't write the SendSimpleMail as a class method but just as a standalone procedure, you don't have any Self just because you don't have any class. The class method you could write for instance for your form class like e.g. TForm1.SendSimpleMail, where inside of that method the Self would have meaning of the TForm1 instance, the form itself.
And the rest of the errors you got because you were accessing the TIdSMTP class, not the object instance. Commonly used practice is to declare a local variable, create an object instance assigning it to that variable, work with that object (variable) and free the object instance.

I would try something like this (tested with Indy 10 shipped with Delphi 2009):

uses
  IdSMTP, IdMessage, IdEMailAddress;

procedure SendSimpleMail;
var
  IdSMTP: TIdSMTP;
  IdMessage: TIdMessage;
  IdEmailAddressItem: TIdEmailAddressItem;
begin
  IdSMTP := TIdSMTP.Create(nil);
  try
    IdSMTP.Host := 'smtp.gmail.com';
    IdSMTP.Port := 25;
    IdSMTP.AuthType := satDefault;
    IdSMTP.Username := 'username@gmail.com';
    IdSMTP.Password := 'password';
    IdSMTP.Connect;
    if IdSMTP.Authenticate then
    begin
      IdMessage := TIdMessage.Create(nil);
      try
        IdMessage.From.Name := 'User Name';
        IdMessage.From.Address := 'username@gmail.com';
        IdMessage.Subject := 'E-mail subject';
        IdMessage.Body.Add('E-mail body.');

        IdEmailAddressItem := IdMessage.Recipients.Add;
        IdEmailAddressItem.Address := 'recipient@email.com';

        IdSMTP.Send(IdMessage);
      finally
        IdMessage.Free;
      end;
    end;
    IdSMTP.Disconnect;
  finally
    IdSMTP.Free;
  end;
end;