fetchmail SMTP error: 553 5.1.8

[Xianwen Chen]

Hi,

I use fetchmail to download emails. Some emails are with domain names 
that cannot be resolved by DNS server. Fetchmail prompts the SMTP error  
code 553 5.1.8 that 'domain of sender address does not exist'.

I guess this error code is from sendmail which refuses to rely emails 
with invalid domain names. Can I configure sendmail to not check domain 
name validility?

Kind regards,

Xianwen