POP3 Login failed - ERR Rate limit exceeded

I bought rambler.ru emails from @BanditIM store (as they seem to be the only option for Ser there).
After an hour of running, all projects are full of the error message: POP3 Login failed - ERR Rate limit exceeded
@Sven is it a problem with Ser or with the accounts?
Anyone can suggest what emails to use without errors? thanks
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Edit: I just saw you mentioned you bought Rambler -- I recommend mail.ru these days for GSA SER, they seem to perform the best.
ill stick with my yahoo mails GSA recommends on the email account section, bit more expensive.. but ordered 1000 7 months ago and can still get around 200 working out of it.. the only annoying thing is have to recheck a 1000 mailing list, got lazy and bought a quick 300 from bandit.. the yahoo mails are amazing to be honest.. gonna buy another 1k from them