Send Microsoft Teams Message via PowerShell GraphAPI to all users based on regex pattern

New-BrodcastMessage.ps1

function New-BroadcastMessage {

  param(
    $user_pattern,
    $sender_id,
    $message
  )
  Connect-MgGraph "Chat.ReadWrite","Chat.ReadWrite","User.Read.All"
  $contacts = Get-MgUser -All:$true | Where-Object {$_.userprincipalname -like $user_pattern}
  
  foreach($c in $contacts)
  {
    $odata = @"
{
  "chatType": "oneOnOne",
  "members": [
    {
      "@odata.type": "#microsoft.graph.aadUserConversationMember",
      "roles": ["owner"],
      "user@odata.bind": "https://graph.microsoft.com/beta/users('$($sender_id)')"
    },
    {
      "@odata.type": "#microsoft.graph.aadUserConversationMember",
      "roles": ["owner"],
      "user@odata.bind": "https://graph.microsoft.com/beta/users('$($c.Id)')"
    }
  ]
}
"@
  
    $chat = New-MgChat -BodyParameter $odata
    New-MgChatMessage -ChatId $chat.Id -Body @" > $null
{
  "content": "$($message)"
}
"@

  }
}