AutoIt
Mailgun Send Send HTML Email with Attachments and HTML Images

Sends an HTML email with images and attachments.
Chilkat AutoIt Downloads

AutoIt
Local $bSuccess = False

;  This example assumes the Chilkat API to have been previously unlocked.
;  See Global Unlock Sample for sample code.

$oHttp = ObjCreate("Chilkat.Http")

$oHttp.Login = "api"
$oHttp.Password = "sending_api_key";  Replace with your actual sending API key.

$oReq = ObjCreate("Chilkat.HttpRequest")
$oReq.HttpVerb = "POST"
$oReq.Path = "/v3/YOUR_DOMAIN_NAME/messages"
$oReq.ContentType = "multipart/form-data"

;  Change YOUR_DOMAIN_NAME to something like "mg.your-domain.com".
$oReq.AddParam "from","Your Name <mailgun@YOUR_DOMAIN_NAME>"
$oReq.AddParam "to","Joe Example <joe@example.com>"
$oReq.AddParam "subject","Hello Joe Example"
$oReq.AddParam "html","<html><body><b>This is the HTML body</b><br><img src=""cid:cidStarfish.jpg""></body></html>"

;  An a attachd file
$oBd = ObjCreate("Chilkat.BinData")
$bSuccess = $oBd.LoadFile("qa_data/hamlet.zip")
If ($bSuccess = False) Then
    ConsoleWrite("Failed to load file attachment." & @CRLF)
    Exit
EndIf

$oReq.AddBdForUpload("attachment","hamlet.zip",$oBd,"application/zip")

;  add an image as CID
$bSuccess = $oBd.LoadFile("qa_data/jpg/starfish.jpg")
If ($bSuccess = False) Then
    ConsoleWrite("Failed to load HTML image." & @CRLF)
    Exit
EndIf

$oReq.AddBdForUpload("inline","cidStarfish.jpg",$oBd,"image/jpeg")

$oResp = ObjCreate("Chilkat.HttpResponse")
$bSuccess = $oHttp.HttpSReq("api.mailgun.net",443,True,$oReq,$oResp)
If ($bSuccess = False) Then
    ConsoleWrite($oHttp.LastErrorText & @CRLF)
    Exit
EndIf

$oSbResponseBody = ObjCreate("Chilkat.StringBuilder")
$oResp.GetBodySb($oSbResponseBody)
$oJResp = ObjCreate("Chilkat.JsonObject")
$oJResp.LoadSb($oSbResponseBody)
$oJResp.EmitCompact = False

ConsoleWrite("Response Body:" & @CRLF)
ConsoleWrite($oJResp.Emit() & @CRLF)

Local $iRespStatusCode = $oResp.StatusCode
ConsoleWrite("Response Status Code = " & $iRespStatusCode & @CRLF)
If ($iRespStatusCode >= 400) Then
    ConsoleWrite("Response Header:" & @CRLF)
    ConsoleWrite($oResp.Header & @CRLF)
    ConsoleWrite("Failed." & @CRLF)
    Exit
EndIf

;  Sample JSON response:
;  (Sample code for parsing the JSON response is shown below)

;  {
;    "id": "<20210429234809.1.2D550E1C94D3D98F@sandbox0e542e4c577f4bbb98c8bf6b6bca727b.mailgun.org>",
;    "message": "Queued. Thank you."
;  }

;  Sample code for parsing the JSON response...
;  Use the following online tool to generate parsing code from sample JSON:
;  Generate Parsing Code from JSON

Local $sId = $oJResp.StringOf("id")
Local $sMessage = $oJResp.StringOf("message")