Here is SQL you can use to update the Lettermail Rates for 2011
update configuration set configuration_value = "0.030:0.59, 0.050:1.03, 0.100:1.25, 0.200:2.06, 0.300:2.85, 0.400:3.25, 0.500:3.50" where configuration_key = "MODULE_SHIPPING_CANADAPOST_LETTERMAIL_CAN";
update configuration set configuration_value = "0.030:1.03, 0.050:1.25, 0.100:2.06, 0.200:3.60, 0.500:7.20" where configuration_key = "MODULE_SHIPPING_CANADAPOST_LETTERMAIL_USA";
update configuration set configuration_value = "0.030:1.75, 0.050:2.50, 0.100:4.10, 0.200:7.20, 0.500:14.40" where configuration_key = "MODULE_SHIPPING_CANADAPOST_LETTERMAIL_INTL";
Also ensure you setup "Lettermail" in your sellonline account as per instructions in an earlier post.