Hello!
I'm certainly clumsy but I failed to install Indy. Maybe I will have more luck tomorrow.

Another solution would be to use a command line tool and execute it from your program. I made a successful test, under Windows, with a tool named
Send-It-Quiet.
Here is my code:
uses
SysUtils, ShellApi, Windows;
var
param: string;
begin
param := Format(
'-s %s -u %s -p %s -f %s -t %s -subject %s -body %s',
[
'smtp.orange.fr',
'xxx@orange.fr',
'mypassword',
'xxx@orange.fr',
'xxx@gmx.fr',
'"The subject"',
'"The body of the message"'
]
);
ShellExecute(
0,
'open',
'senditquiet.exe',
PChar(param),
'C:\SendItQuietDirectory',
SW_SHOWNORMAL
);
end.
The code was tested under Windows 10, with Lazarus 1.6.
By the way, I don't understand the difference between the user (-u) and the sender (-f).
