Old behaviour:

bmZvIDggMCBSCj4+CnN0YXJ0eHJlZgoyMzI0MAolJUVPRgo=
--=_5bdf621d1bfaa739515269c2c3bf79f5--

------367FD1B765DEB7C1C28E32CE31E112FA
Content-Type: application/x-pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"

MIIMugYJKoZIhvcNAQcCoIIMqzCCDKcCAQExCzAJBgUrDgMCGgUAMAsGCSqGSIb3

New behaviour:

bmZvIDggMCBSCj4+CnN0YXJ0eHJlZgoyMzI0MAolJUVPRgo=
--=_d8ce0840ff9fb87911a6b36138bef38c--


------6EB31323CF771830B30002B13567BF6E
Content-Type: application/x-pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"

MIIMugYJKoZIhvcNAQcCoIIMqzCCDKcCAQExCzAJBgUrDgMCGgUAMAsGCSqGSIb3