How to send an email from a remote event receiver? can we still use MailMessage?

Question

I have a server-side event receiver inside our SharePoint 2013 farm, and inside the ER i am sending emails using this code:-

 using (MailMessage myMailMessage = new MailMessage())
            {


                SPOutboundMailServiceInstance smtpServer = mailserverinstance;
                System.Net.Mail.SmtpClient smtp = new System.Net.Mail.SmtpClient(smtpServer.Server.Address);


                myMailMessage.IsBodyHtml = true;
                myMailMessage.Subject = title;

                myMailMessage.Body = emailbody;

                myMailMessage.From = new MailAddress(fromField);
                string[] emailaddresses = to.Split(';');
                foreach (var toemail in emailaddresses)
                {
                    if (!string.IsNullOrEmpty(toemail))
                    {
                        myMailMessage.To.Add(new MailAddress(toemail));
                    }

                }
                if (!string.IsNullOrEmpty(cc))
                    myMailMessage.CC.Add(new MailAddress(cc));
                if (myMailMessage.To.Count > 0)
                {
                    smtp.Send(myMailMessage);
                }

            }

now i want to re-code my server-side event receiver, to work inside our SharePoint online tenant, so i am not sure how i will be sending emails inside my remote event receiver using CSOM? any sample codes?

Answer 1

This has been the most famous method for a sending email. You can use SharePoint Utility class to send an email. But you cannot send to external users. If you are sending to external users, they should be added to your mail exchange, but it will take some time to reflect the change.

var spContext = SharePointContextProvider.Current.GetSharePointContext(Context);
using (var clientContext = spContext.CreateUserClientContextForSPHost())
{
    var emailp = new EmailProperties();
    emailp.BCC = new List<string>{"a@mail.com"};
    emailp.To = new List<string>{"b@mail.com"};
    emailp= "from@mail.com";
    emailp.Body = "<b>html</b>";
    emailp.Subject = "subject";

    Utility.SendEmail(_clientContext, properties);
    _clientContext.ExecuteQuery();
}

You can use the same method with remote event receivers only by changing SharePoint client context initiation.

Answer 2

Yes you can use CSOM to send emails in SPO. @Karthik Jaganathan has provided a good demo.

As for the context, for example, if you're developing a console app, then you may need to pass credential to generate client context like below:

SendEmailExternalUser.cs

While for a remote event receive, we can get the context without credential:

For more details, See below official docs and samples:

• Create a remote event receiver
• AppEventReceiver

How does remote event receiver get authorized with SharePoint?

• Context Token OAuth flow