Error al enviar desde gmail

[Gary Ariel Sandi Vigabriel <gary.gsv@gmail.com>]

Tengo el siguiente error al enviar desde gmail pero solo pasa en gmail
desde un navegador web y no en evolution como puedo usar gmail para
enviar mensajes a la lista sin que me bote ese error?

This is an automatically generated Delivery Status Notification

Delivery to the following recipient failed permanently:

    debian-l10n-spanish@lists.debian.org

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the
recipient domain. We recommend contacting the other email provider for
further information about the cause of this error. The error that the
other server returned was: 550 550 5.7.1 37 Your email is not using a
proper character set. Please correct this (try setting your mail program
to use plain text) and resend your message. (state 18).

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