Here is what finally I did.

I create a custom WorkflowType.

In this link, I found a Forms default SendEmail workflowtype;

https://gist.github.com/TimGeyssens/6ff5392c4d9bbf89bdfc

From there and using the idea from this other link;

https://our.umbraco.org/forum/umbraco-pro/contour/44586-Working-with-save-as-file-workflow

And finally I made a custom workflowtype that satisfies my need. Here is the code;

using System; using System.Collections.Generic; using System.Linq; using System.Text; using Umbraco.Forms.Core.Enums; using System.Text.RegularExpressions; using Umbraco.Forms.Data.Storage; using System.Xml; using System.Xml.XPath; using System.Web; using System.Net.Mail; using Umbraco.Core.Configuration; using System.IO; using System.Net.Mime;

namespace Umbraco.Forms.Core.Providers.WorkflowTypes { public class SendEmailKML : WorkflowType { [Attributes.Setting("Email", description = "Enter a list of receivers email separated by a semicolon", view = "TextField")] public string Email { get; set; }

    [Attributes.Setting("SenderEmail", description = "Enter the sender email (if blank it will use the settings from /config/umbracosettings.config)", view = "TextField")]
    public string SenderEmail { get; set; }

    [Attributes.Setting("Subject", description = "Enter the subject", view = "TextField")]
    public string Subject { get; set; }        

    [Attributes.Setting("Attachment", description = "Attach file uploads to email", view = "Checkbox")]
    public string Attachment { get; set; }

    public SendEmailKML()
    {
        this.Id = new Guid("A7309169-E91A-484C-BFFA-934CAF733864");
        this.Name = "Request a quote email";
        this.Description = "Send the info on the \"Request a quote\" form to a list of emails and attach a KML file generated from the map";
    }

    public override List<Exception> ValidateSettings()
    {
        List<Exception> l = new List<Exception>();
        if (string.IsNullOrEmpty(Email))
            l.Add(new Exception("'Email' setting has not been set"));

        if (string.IsNullOrEmpty(Subject))
            l.Add(new Exception("'Subject' setting has not been set'"));

        return l;
    }

    public override WorkflowExecutionStatus Execute(Record record, RecordEventArgs e)
    {
        System.Net.Mail.MailMessage m = new System.Net.Mail.MailMessage();            
        m.From = new System.Net.Mail.MailAddress(string.IsNullOrEmpty(SenderEmail) ? UmbracoConfig.For.UmbracoSettings().Content.NotificationEmailAddress : SenderEmail);
        m.Subject = Subject;
        m.IsBodyHtml = true;

        if (Email.Contains(';'))
        {
            string[] emails = Email.Split(';');
            foreach (string email in emails)
            {
                m.To.Add(email.Trim());
            }
        }
        else
        {
            m.To.Add(Email);
        }

        XmlNode xml = record.ToXml(new System.Xml.XmlDocument()); 

        XPathNavigator navigator = xml.CreateNavigator();

        XPathExpression selectExpression = navigator.Compile("//fields/child::*");
        selectExpression.AddSort("@pageindex", XmlSortOrder.Ascending, XmlCaseOrder.None, "", XmlDataType.Number);
        selectExpression.AddSort("@fieldsetindex", XmlSortOrder.Ascending, XmlCaseOrder.None, "", XmlDataType.Number);
        selectExpression.AddSort("@sortorder", XmlSortOrder.Ascending, XmlCaseOrder.None, "", XmlDataType.Number);

        XPathNodeIterator nodeIterator = navigator.Select(selectExpression);

        var fileKML = "";
        string list = "<p></p> <ul> ";
        while (nodeIterator.MoveNext())
        {
            var caption = Umbraco.Forms.Data.DictionaryHelper.GetText(nodeIterator.Current.SelectSingleNode("caption").Value);
            if ((caption != "Attach files") && (caption != "kmlString"))
            {
                list += "<li><strong>" + caption + ": </strong>";
            }

            XPathNodeIterator values = nodeIterator.Current.Select(".//value");

            while (values.MoveNext())
            {
                var val = values.Current.Value.Trim();
                if ((caption != "Attach files") && (caption != "kmlString"))
                {
                    list += Umbraco.Forms.Data.DictionaryHelper.GetText(val).Replace("\n", "<br/>") + "<br/><br/>";
                }

                if ((this.Attachment == true.ToString()) && (val.Contains("/forms/upload")))
                {
                    // add attachment
                    string filelocation = HttpContext.Current.Server.MapPath(val);
                    m.Attachments.Add(new Attachment(filelocation));
                }
                if ((caption == "kmlString"))
                {
                    fileKML = val.Replace("&quot;", "\"");                        
                }
            }
            list += "</li>";
            caption = "";
        }

        list += "</ul>";

        m.Body = list;

        var stream = new MemoryStream();

        var fileBytes = Encoding.UTF8.GetBytes(fileKML);

        stream.Write(fileBytes, 0, fileBytes.Length);
        stream.Seek(0, SeekOrigin.Begin);

        var contentType = new ContentType
        {
            MediaType = MediaTypeNames.Application.Octet,
            Name = "Map_Coordinates.kml"                
        };
        var attachment = new Attachment(stream, contentType);
        m.Attachments.Add(attachment);

        System.Net.Mail.SmtpClient s = new System.Net.Mail.SmtpClient();

        s.Send(m);

        return WorkflowExecutionStatus.Completed;
    }
}

}

I want to send a huge thanks to;

Jesper Hauge, Tim Geyssens, Dennis Aaen