POP3 RETR (127) failed – + OK Maildrop ready, (JPOP server ready). > Try again

Hello @sven, this error message appears in the list of logs.
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POP3 RETR (127) failed – + OK Maildrop ready, (JPOP server ready). > Try again
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What does it mean? how to avoid that?
Please, give your opinion.
Thank you.