Hello SharePointers,

Below is the CSOM code to send email to External users in SharePoint online using CSOM

string Url = “https://tenant.sharepoint.com/sites/comms/”;
var cc = new ClientContext(Url);
string passwordPlainText = “userpassword”;
string currentUserLoginName = “user@tenant.onmicrosoft.com”;
var passWord = new SecureString();
foreach (char c in passwordPlainText.ToCharArray()) passWord.AppendChar(c);
cc.Credentials = new SharePointOnlineCredentials(currentUserLoginName, passWord);

web.EnsureUser(“i:0#.f|membership|paige.turner_contoso.com#ext#@tenant.onmicrosoft.com”);
clientContext.ExecuteQuery();

var emailProperties = new EmailProperties();
//Email of authenticated external user
emailProperties.To = new string[] { “Laks.Sethu@contoso.com” };

emailProperties.Body = “This is the email body”;
emailProperties.Subject = “This is the email subject”;
Utility.SendEmail(clientContext, emailProperties);

cc.ExecuteQuery();

Happy SharePointing 🙂