Test case Sending email message with attachments (more than one) as a template.txt, format TXT throws following error.

[mithunbharadwaj]

    {
    "result": "ERROR",
    "message": "Unsupported conversion format 'txt'.",
    "uuid": "73e0c27f-c527-474e-834d-a69ddaab4641"
    }

[ateska]

Yes, this should be supported.