Sub CommandButton1_Click()
Dim olApp As Outlook.Application
Dim objMail As Outlook.MailItem

    ActiveWorkbook.Save
    
    Set olApp = Outlook.Application
    Set objMail = CreateItem(olMailItem)
    With objMail
        .BodyFormat = olFormatPlain
        .Body = "body"
        .Subject = "Subject"
        .To = "MyAddress@Domain.RU"
        .Attachments.Add ActiveWorkbook.FullName, olByValue,  1 , "Test"
        .Send
    End With
    olApp.Quit ' можно и без этого
End Sub

Sub CommandButton1_Click()
Dim olApp As Object 'Outlook.Application
Dim objMail As Object 'Outlook.MailItem
Const myMailItem =  0 
Const myFormatPlain =  1 
Const myByValue =  1 

    ActiveWorkbook.Save
    
    Set olApp = CreateObject("Outlook.Application")
    Set objMail = olApp.CreateItem(myMailItem)
    With objMail
        .BodyFormat = myFormatPlain
        .Body = "body"
        .Subject = "Subject"
        .To = "MyAddress@Domain.RU"
        .Attachments.Add ActiveWorkbook.FullName, myByValue,  1 , "Test"
        .Send
    End With
    olApp.Quit
End Sub