postfix // bypass FQDN checks for certain IPs?

[vmos2]

Good morning, I'm trying to get email alerts from a bunch of drac systems.
All the alerts come from an address like alert@rac-23232.

Our relay server (ubuntu 10+postfix) rejects this as it's not a FQDN.

We can get around that if there is reverse DNS for the IP it comes from. However, there's a zone we're having difficulty configuring reverse DNS for, it may prove to be impractical.

So I'm wondering is it possible to disable the FQDN lookups for a range of IPs? Even a single IP might do the job as all these mails seem to come from the same gateway IP.