The reason why only one of your sequences is sending and there other ones are not is related to the fact that your current mailbox capacity is at full use. You can send 30 cold emails each day with one mailbox. If there are 30 scheduled emails for today, that means that the limit has been reached.
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If you have multiple campaigns that you want to run at the same time, you can split the amount of mailboxes you use for each sequence or simply purchase more domains and mailboxes.
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