Good point! I have added it to the features list https://github.com/unacms/jot-client-una/issues/310

You may correct code in the same file modules/boonex/classes/BxMessngerModule.php.

Find the function serviceGetMessageContent($aEvent)

and replace this line:

$sAlterBody = $sTruncatedMessage ? $sTruncatedMessage : _t('_bx_messenger_txt_sample_email_push', html2txt($sMessage));

with this code:

$sAlterBody = $sTruncatedMessage ? 'New message waiting in talk' : _t('_bx_messenger_txt_sample_email_push', html2txt($sMessage));