A user sending email from yahoo web mail to one of my clients on Smartermail is getting bounced from smartermail with error below.  Looks like a possible attachment encoding problem where Smartermail may be interpreting the attachment encoding as a too long input string.  This just started happening after the upgrade to 12.4.5364. Wasn't a problem before with this same sender/ pdf attachment combo. Any thoughts appreciated.

 

Sorry, we were unable to deliver your message to the following address.

<removed>:
Remote host said:
500 5.5.0 Line too long
[BODY]