How to send MIMECONTENT using Graph SDK V5 (.NET)

Question

Currently, I'm working on sending reserved mail system using graph sdk.

I'm trying to send saved .eml file(Mimecontent) using graph sdk (v5).

I found some way on https://learn.microsoft.com/en-us/graph/api/user-sendmail?view=graph-rest-1.0&tabs=http but it only show way for http.

Therefore, I'm using MIMEKIT library and reconstruct the email and send but I don't think this is a best way to do it.

byte[] newbuffer = File.ReadAllBytes(filepath);
using (var memoryStream = new MemoryStream(newbuffer)) {
    var mimeMessage = MimeKit.MimeMessage.Load(memoryStream);
    var message = new Microsoft.Graph.Models.Message
    {
        Subject = mimeMessage.Subject,
        Body = new Microsoft.Graph.Models.ItemBody
        {
            ContentType = mimeMessage.HtmlBody != null ? Microsoft.Graph.Models.BodyType.Html : Microsoft.Graph.Models.BodyType.Text,
            Content = mimeMessage.HtmlBody ?? mimeMessage.TextBody
        },
        ToRecipients = mimeMessage.To.Mailboxes.Select(mailbox => new Microsoft.Graph.Models.Recipient
        {
            EmailAddress = new Microsoft.Graph.Models.EmailAddress { Address = mailbox.Address }
        }).ToList()
    };
    var draftMessage = await gsc.Users[userinfo.UserPrincipalName].Messages.PostAsync(message);
    foreach (var attachment in mimeMessage.Attachments.OfType<MimeKit.MimePart>())
    {
        var attachmentStream = new MemoryStream();
        attachment.Content.DecodeTo(attachmentStream);
        byte[] fileBytes = attachmentStream.ToArray(); 
        attachmentStream.Dispose(); 
        var fileAttachment = new Microsoft.Graph.Models.FileAttachment
        {
            OdataType = "#microsoft.graph.fileAttachment",
            ContentBytes = fileBytes,
            ContentType = attachment.ContentType.MimeType,
            Name = attachment.FileName
        };
        await gsc.Users[userinfo.UserPrincipalName].Messages[draftMessage.Id].Attachments.PostAsync(fileAttachment);
    }
    await gsc.Users[userinfo.UserPrincipalName].Messages[draftMessage.Id].Send.PostAsync();
}

I'm wondering I may use ToPostRequestInformation for more simple way? Or anyone know the other way? please help me

Thanks