Add button in backstage menu: File > Share > Email

        #region Component Designer generated code
        /// <summary>
        /// Required by designer support - do not modify
        /// the following method
        /// </summary>
        private void InitializeComponent()
        {
            this.components = new System.ComponentModel.Container();
            this.adxBackstageView1 = new AddinExpress.MSO.ADXBackstageView(this.components);
            this.adxBackstageTab1 = new AddinExpress.MSO.ADXBackstageTab(this.components);
            this.adxBackstageTaskFormGroup1 = new AddinExpress.MSO.ADXBackstageTaskFormGroup(this.components);
            this.adxBackstageTaskFormGroupCategory1 = new AddinExpress.MSO.ADXBackstageTaskFormGroupCategory(this.components);
            this.adxBackstageTaskFormGroupTask1 = new AddinExpress.MSO.ADXBackstageTaskFormGroupTask(this.components);
            this.adxBackstageGroup1 = new AddinExpress.MSO.ADXBackstageGroup(this.components);
            this.adxBackstageRegularButton1 = new AddinExpress.MSO.ADXBackstageRegularButton(this.components);
            // 
            // adxBackstageView1
            // 
            this.adxBackstageView1.Controls.Add(this.adxBackstageTab1);
            this.adxBackstageView1.Id = "adxBackstageView_a1cfd3c8a1874dcaaa9aac7f277d1cb2";
            this.adxBackstageView1.Ribbons = AddinExpress.MSO.ADXRibbons.msrExcelWorkbook;
            // 
            // adxBackstageTab1
            // 
            this.adxBackstageTab1.Caption = "Tab1";
            this.adxBackstageTab1.FirstColumn.Add(this.adxBackstageTaskFormGroup1);
            this.adxBackstageTab1.Id = "adxBackstageTab_4934fb362a5e44c082ee01a3514cf17c";
            this.adxBackstageTab1.IdMso = "TabShare";
            this.adxBackstageTab1.Ribbons = AddinExpress.MSO.ADXRibbons.msrExcelWorkbook;
            // 
            // adxBackstageTaskFormGroup1
            // 
            this.adxBackstageTaskFormGroup1.Caption = "TaskFormGroup1";
            this.adxBackstageTaskFormGroup1.Controls.Add(this.adxBackstageTaskFormGroupCategory1);
            this.adxBackstageTaskFormGroup1.Id = "adxBackstageTaskFormGroup_a4e148ea356348e0b8764d21c8afe39f";
            this.adxBackstageTaskFormGroup1.IdMso = "GroupShare";
            this.adxBackstageTaskFormGroup1.Ribbons = AddinExpress.MSO.ADXRibbons.msrExcelWorkbook;
            // 
            // adxBackstageTaskFormGroupCategory1
            // 
            this.adxBackstageTaskFormGroupCategory1.Caption = "TaskFormGroupCategory1";
            this.adxBackstageTaskFormGroupCategory1.Controls.Add(this.adxBackstageTaskFormGroupTask1);
            this.adxBackstageTaskFormGroupCategory1.Id = "adxBackstageTaskFormGroupCategory_746ae5ac10d24f8fb68cf80c2005b9be";
            this.adxBackstageTaskFormGroupCategory1.IdMso = "Share";
            this.adxBackstageTaskFormGroupCategory1.Ribbons = AddinExpress.MSO.ADXRibbons.msrExcelWorkbook;
            // 
            // adxBackstageTaskFormGroupTask1
            // 
            this.adxBackstageTaskFormGroupTask1.Caption = "TaskFormGroupTask1";
            this.adxBackstageTaskFormGroupTask1.Controls.Add(this.adxBackstageGroup1);
            this.adxBackstageTaskFormGroupTask1.Id = "adxBackstageTaskFormGroupTask_f8b60bf0210c43e281abd36eaad35a8d";
            this.adxBackstageTaskFormGroupTask1.IdMso = "SendUsingEmail";
            this.adxBackstageTaskFormGroupTask1.ImageTransparentColor = System.Drawing.Color.Transparent;
            this.adxBackstageTaskFormGroupTask1.Ribbons = AddinExpress.MSO.ADXRibbons.msrExcelWorkbook;
            // 
            // adxBackstageGroup1
            // 
            this.adxBackstageGroup1.Caption = "Group1";
            this.adxBackstageGroup1.Id = "adxBackstageGroup_c57298f782234e82bd814ca005640ff2";
            this.adxBackstageGroup1.InsertAfterIdMso = "GroupSendAsInternetFax";
            this.adxBackstageGroup1.PrimaryItem.Add(this.adxBackstageRegularButton1);
            this.adxBackstageGroup1.Ribbons = AddinExpress.MSO.ADXRibbons.msrExcelWorkbook;
            // 
            // adxBackstageRegularButton1
            // 
            this.adxBackstageRegularButton1.Caption = "RegularButton1";
            this.adxBackstageRegularButton1.Id = "adxBackstageRegularButton_ee4267cb39ac468e9313ddf7c5639e16";
            this.adxBackstageRegularButton1.ImageTransparentColor = System.Drawing.Color.Transparent;
            this.adxBackstageRegularButton1.Ribbons = AddinExpress.MSO.ADXRibbons.msrExcelWorkbook;
            // 
            // AddinModule
            // 
            this.AddinName = "MyAddin21";
            this.SupportedApps = AddinExpress.MSO.ADXOfficeHostApp.ohaExcel;

        }
        #endregion

        private AddinExpress.MSO.ADXBackstageView adxBackstageView1;
        private AddinExpress.MSO.ADXBackstageTab adxBackstageTab1;
        private AddinExpress.MSO.ADXBackstageTaskFormGroup adxBackstageTaskFormGroup1;
        private AddinExpress.MSO.ADXBackstageTaskFormGroupCategory adxBackstageTaskFormGroupCategory1;
        private AddinExpress.MSO.ADXBackstageTaskFormGroupTask adxBackstageTaskFormGroupTask1;
        private AddinExpress.MSO.ADXBackstageGroup adxBackstageGroup1;
        private AddinExpress.MSO.ADXBackstageRegularButton adxBackstageRegularButton1;
    }