[mailop] VERP generating syntactically invalid return-path?

[Dave Pooser]

A contractor just started getting bounce messages when he tries to email
$DAYJOB -- the message is accepted by our Exim frontend but then rejected
by our Exchange 2013 server with the error message below (example.com and
example.net are placeholders for two different .com domains; outside
sender is usern...@example.net and my recipient is u...@example.com):

Failed to deliver to 'u...@example.com'
SMTP module(domain mail1.example.com:25) reports:
return-path address 

Re: [mailop] VERP generating syntactically invalid return-path?

[Dave Pooser]

On 2/2/16, 7:59 PM, "mailop on behalf of John Levine"
 wrote:

>>return-path address