InternetAddressList does not allow insert at end

[bradlis7]

Describe the bug
When attempting to insert at the end of an InternetAddressList, it returns argument out of range. It is allowed in List<> implementation.

Platform (please complete the following information):

• OS: Windows
• .NET Runtime: CoreCLR
• .NET Framework: .NET Core 3.1
• MailKit Version: 2.4.1

To Reproduce

Code Examples

// Failures
var to = new InternetAddressList();
to.Add(new MailboxAddress("[email protected]"));
to.Insert(1, new MailboxAddress("[email protected]"));
to = new InternetAddressList();
to.Insert(0, new MailboxAddress("[email protected]"));

// This works
to = new InternetAddressList();
to.Add(new MailboxAddress("[email protected]"));
to.Insert(0, new MailboxAddress("[email protected]"));

Expected behavior
If I insert at the current count, it should act like Add.

Screenshots
N/A

Additional context
N/A

[jstedfast]

Thanks for the bug report!

[bradlis7]

That was fast :). Thanks!