James: No local-part (user account) found at position 1

[Pete Williams]

HI
i'm seeing these errors in my James smtpserver log file:
Error parsing recipient address:  [to:@localhost] [from:xxxxxxxx]No local-part 
(user account) found at position 1
It occurs when there are a lot of recipients, and particularly when there are a 
log of domain names with a dash in them.
Each address listed in the 'to' section a few lines above this error looks good 
(not malformed).
If anyone can help to debug this I'd be grateful.
James 2.3.4
Cheers, Pete