NAVCA discourages the sending of attachments to the email
networks it hosts. Large attachments can greatly slow down the
networks.
In light of this there is a size limit of 250KB for attachments. If
subscribers try to send a message with an attachment larger than
this, the message will be rejected.
It is usually possible to copy the contents of the attachment
directly into the message itself. Another suggested option for
sharing large attachments is adding it to your website and sending
the URL in a posting rather than the attachment itself.