You should set our minimum delay time to 30 seconds, your maximum time to 60 seconds (see screenshot below). This is the amount of time we will delay between sendings to ensure you are with YouTube’s terms of service.
Whether you are sending through Tube Toolbox or directly through www.youtube.com, YouTube will send a message if you have sent too many messages and need to wait some time before sending again. When we receive that message from YouTube saying you need to wait before sending again OR we check your sent box and YouTube is not really sending your messages, our software displays a message saying "waiting for restriction to be removed" or "YouTube did not send message".
When this occurs we wait the Auto-Retry time before we try sending again (see screenshot below). This blog explains how to set the Auto-Retry wait time. The minimum and maximum delay times are set in your setup screen. http://www.tubetoolbox.com/Blog/post/Maximize-Bulk-Actions.aspx
YouTube has recently instituted new sending restrictions. Please review this blog entry for a description of the changes (especially section discussing waiting 24 hours before sending again). http://www.tubetoolbox.com/Blog/post/New-YouTube-Send-Message-Restrictions.aspx
This issue is not a Tube Toolbox issue but a YouTube issue. Below are some links to YouTube support posts expressing frustration at the limited number of messages that can be sent.
YouTube is limiting your activity and you just need to wait until their restrictions are reduced. One of the results of using a product like ours is that you are able to send messages all the time. This can cause YouTube to become more restrictive in allowing activity from Your account/network(IP) address. However, if you follow the instructions in the blog entry above, you will be able to maximize your sending.
Also, please remember YouTube's limits based on our testing are located here - Bulk Sending Guide