[exim] Exim asking for auth login screen

Hi,



I use exim for a long time on a CentOS with cPanel as mailserver.



Las month Outlook clients are asking for auth login screen and "sometimes" I
got and 550 error.



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Server Error: 550

Server Answer: 550 Access denied - Invalid HELO name (See RFC2821 4.1.1.1)

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If I access using a webmail all works well.



I use POP: 110 and SMPT 587 ports without SSL connections.



Could anyone help me with this strange behavior?



Thanks for any help.



Ronaldo Luiz