YouTube limits the number of channels to which you can be subscribed to 2,000. This limit gets increased when you get enough people subscribed to your channel. This does have an impact on TubeAssist subscribe to channel campaigns.
If you are running a subscribe to channels campaign in TubeAssist, the campaign will be stopped and you will be emailed when you hit your limit. At this point, you have a few options:
1. You can log into YouTube and unsubscribe from a bunch of channels so that you can continue running your subscribe to channels campaign.
2. You can stop running your subscribe to channels campaign and switch to something else like an add contacts campaign.
3. You can use our subscription cleaning tool. To do this, log into TubeAssist, click the 'Manage' button for your channel, and click the 'Subscriptions' link in the left hand navigation.
Hopefully that helps, but if you have any additional questions please let us know.