Postage costs are stored in RepricerExpress and used during repricing calculations.
Note though that these are 'cached' meaning that it gets these postage values once and stores and reuses these values - it doesn't get them each time it reprices - as it would slow down repricing.
So if you change your postage in any way - or if using weight based postage and you alter the weight of items on Amazon - then you need to let RepricerExpress know to get new postage values.
This is done via the 'Refresh Postage' option on the Amazon account settings screen. Clicking this lets the pricing tool know to get new postage values.
N.B. Getting postage values will slow down repricing until it has obtained and stored these again - after which repricing will run at normal speed again.
Amazon also state that it can take up to 4 hours for new postage rates to update on their systems - so you will need to ensure that postage has been updated on Amazon before refreshing postage in RepricerExpress.
This link may be of use: https://sellercentral.amazon.co.uk/gp/help/35011/ref=pt_35011_cont_891#Latency
(You may need to change Amazon.co.uk in the above link to your Amazon marketplace instead).
See the information below from Amazon:
When you change your shipping settings, the changes take effect four hours after you click Save Changes. This latency is explained below.
You can make changes to your Item/Weight Based or Price Bandedshipping settings within the first hour after you click Save Changes, and the changes will all take effect at the same time. If you wait longer than an hour to make changes, then you cannot make changes to what will take effect. This latency gives you an hour to change your mind, but after an hour, your changes are "locked in" and will take effect after an additional three hours pass.
Here's an example of how this works:
- At 12 noon, you click Save Changes after changing the shipping rates. The changes take effect at 4:00 p.m.
- At 12:30 p.m., you make another change to the shipping rates. The change still will take effect at 4:00 p.m.
- At 1:00, your changes are "locked in." At this point, you can no longer make changes, and you cannot stop the shipping settings from taking effect at 4:00 p.m.
- At 1:05, you make yet another change. When you click Save Changes, then the changes will take effect at 5:05.
- At 4:00 p.m., your first set of changes takes effect.
- At 5:05 p.m., your second set of changes takes effect.
Note that while this latency period gives you a one-hour window to adjust the shipping settings or to change your mind, after the one-hour window, your changes to the shipping settings are "locked in" and you cannot change them or stop them.