Function sendMail(MailSubject As String, MailBody As String, ToAddress As String, _
                    Optional CcAddress As String = vbNullString, Optional BccAddress As String = vbNullString, Optional attFile As Variant = vbNullString)

Const mailUser As String = "<Gmailのメアド>"
Const mailPass As String = "<アプリパスワード>"

Dim cdoMsg As Object: Set cdoMsg = CreateObject("CDO.Message")
Dim objFso As Object: Set objFso = CreateObject("Scripting.FileSystemObject")
Dim i As Long

With cdoMsg
    With .Configuration.Fields
        .Item("http://schemas.microsoft.com/cdo/configuration/languagecode") = "shift-jis" '---文字コード指定
        .Item("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2 '---外部SMTP指定
        .Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") = "smtp.gmail.com" '---SMTPサーバ名
        .Item("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = "465" '---ポート№
        .Item("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") = True '---SMTP認証
        .Item("http://schemas.microsoft.com/cdo/configuration/smtpusessl") = True '---SSL
        .Item("http://schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout") = 60 '---タイムアウト
        .Item("http://schemas.microsoft.com/cdo/configuration/sendusername") = mailUser '---ユーザー
        .Item("http://schemas.microsoft.com/cdo/configuration/sendpassword") = mailPass '---パスワード
        .Update
    End With
    .Subject = MailSubject
    .TextBody = MailBody
    .TextBodyPart.Charset = "ISO-2022-JP"
    .From = mailUser
    .To = ToAddress
    .CC = CcAddress
    .BCC = BccAddress
    
    '---添付ファイルが複数（配列形式）かの分岐
    If IsArray(attFile) = True Then
        For i = LBound(attFile) To UBound(attFile)
            '---ファイルが存在してれば添付する
            If objFso.FileExists(attFile(i)) Then
                .AddAttachment attFile(i)
            End If
        Next
    Else
        '---ファイルが存在してれば添付する
        If objFso.FileExists(attFile(i)) Then
            .AddAttachment attFile(i)
        End If
    End If
    .Send
End With

Set cdoMsg = Nothing
Set objFso = Nothing
End Function