You can set the maximum number of posts dlvr.it makes per update period for each of your feeds. You just need to set the "Max number of items to Post per update Period" setting for your feed.
1) Log in to your dlvr.it account
2) Edit your feed
-Click on the Feed to expand the menu and click on the 'Settings' Pencil icon tab. If you have Routes set up, rather than Feeds, click on the Gear icon next to the Feed you wish to edit.
3) Go to the Updates tab
4) Enter the Max Number of Items to Post per Update Period.
5) Click on Save, and your settings will be implemented