I am using 7.0RC1 on 2 different machines (P4-1700 and a P3-867) both have am simillar problemm. both with spamassassin and Clamav on and off.
One server is running as server/gateway the other as server only.
That emails above 5 Mb are extremely slow sending to the server.
With previously versions of SME i have never had this problem.
An email of 15 Mb will even give a time-out of the server.
Please help