VBA 

Outlook users:

 Public Sub SendMail(iv_user_id_hr As String)
  Dim appOutlook As New Outlook.Application
  Dim objMailtemplate As Outlook.MailItem
  Dim objMail As Outlook.MailItem
 
  Set objMailtemplate = GetCurrentOutlookMail()
  Set objMail = appOutlook.CreateItem(olMailItem)
  With objMail
    .To = iv_user_id_hr
    .Recipients.ResolveAll
    .CC = ""
    .BCC = ""
    .Subject = objMailtemplate.Subject
    .Body = objMailtemplate.Body
    .BodyFormat = objMailtemplate.BodyFormat
    .HTMLBody = objMailtemplate.HTMLBody
    .Importance = objMailtemplate.Importance
    .ReminderSet = objMailtemplate.ReminderSet
    .ReminderTime = objMailtemplate.ReminderTime
    .VotingOptions = objMailtemplate.VotingOptions
    .VotingResponse = objMailtemplate.VotingResponse
  If frm_mailing_wizard.chk_do_not_send = False Then
    .Send
  Else
    .Display
  End If
  End With
End Sub

------------

via URL:

Public Declare Function ShellExecute Lib "shell32.dll" _
  Alias "ShellExecuteA" (ByVal hwnd As Long, _
  ByVal lpOperation As String, ByVal lpFile As String, _
  ByVal lpParameters As String, ByVal lpDirectory As String, _
  ByVal nShowCmd As Long) As Long

Public Sub OpenURL(url As String, Optional ByVal ShowMode As OpenUrlShowConstants = swNormal)
  ShellExecute GetDesktopWindow(), "Open", url, "", "", ShowMode
End Sub

...

  If lv_url <> "" Then
    OpenURL (lv_url)
  End If
...

for lv_url use this syntax:

lv_url = 'mailto:' && lv_address_to && '&subject=' && iv_subject && '&body=' && lv_body