Send email with Outlook

I wrote few days ago about stricter rules for using our company SMTP server. Making it more secure is an option, unfortunately they shortly pushed another condition to the mix - the sender must have a static IP address.

While this is not a problem for servers, for normal users it is not achievable. So I kept looking for further options how to send an email from user machine. Fortunately, all users have Outlook installed, so I could use that.

First, in C# project, select Dependencies/Add COM Reference ..., check Microsoft Outlook 16.0 Object Library and click OK. An entry Interop.Microsoft.Office.Interop.Outlook should be added in the list.

Then we just need to use it:

using Outlook = Microsoft.Office.Interop.Outlook;

The using command above creates alias for the specified namespace, so further calls have reasonable naming:

Outlook.Application outlook = new();
var mail = outlook.CreateItem(Outlook.OlItemType.olMailItem);
mail.To = "one@work.com";
mail.Cc = "two@work.com";
mail.BodyFormat = Outlook.OlBodyFormat.olFormatPlain;
mail.Subject = "Some subject";
mail.Body = "Text of the email";
mail.Attachments.Add(Path.GetFullPath("some_file.xlsx");
mail.Send();

This code composes a mail and sends it. Another option is to show the email and let user to check it and send themselves. Just add

mail.Display();

and omit last Send method call.