Scrub reassemble tcp

Hi all,

Is anyone using "reassemble tcp" with scrub ? Been using this for years 
without problems, now all of a sudden having trouble with SMTP echange 
with someone, here is the definition I use, on OpenBSD 5.4:

match in all scrub (no-df max-mss 1440 random-id reassemble tcp)

If I telnet port 25 to the other side, I can see sendmail's greeting, 
but as soon as I go with "EHLO me.dot.com", no more response, it hangs, 
and I see PF sending "icmp host unreachable" to the other side. And if I 
remove "reassemble tcp" all goes fine.

I talked to the guys on the other side, their firewall is netasq, and 
they don't see anything unusual.

Thanks,