@TalTIU
Each plan has limit for number of subscribers but also limit of number of emails you can send per billing cycle.. I assume you are on a free plan with limit of 500 email sends per month and you have already send emails before this month so now when you try to send the number of total sends for this billing cycle goes above your limit of 500 by 29.. for example you send one email to 190, another email to 190 that is 380.. so now if you are tying to send to 149 for example that would mean you want to send 529 emails this month and your limit is 500.. so you are going 29 emails above your limit and that is why you cant send
Oh my goodness, that makes perfect sense now. Thank you!!!