VLAN MTU Problem?

Hi All,

I'm experiencing this strange issue where I can send an email fine
from either VLAN as long as its text only, no attachment, but when I
try to send with an attachment, it just hangs the email server process
(qmail-smtpd in this case). Is this something that may be caused by an
MTU problem? I've got a RealTek 8100 series card and a eepro100 as my
two VLAN interfaces, and this phenomenon doesnt occur at an office
that we don't have VLANs. Also, When I ping vlan1 from a vlan2 machine
(or vice versa) it works, but when I change the size to up around 1468
or so it doesnt work. Anyone have any ideas?

Thanks in advance!
Derek