Email/Exim - shadow file issue

I noticed that webmail (SquirrelMail) was showing the following error when sending email:

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Unknown response
435 Unable to authenticate at present
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Then I checked exim_mainlog which showed:

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2010-03-08 06:09:33 fixed_login authenticator failed for localhost.localdomain (www.mydomain.com) [127.0.0.1]: 435 Unable to authenticate at present (set_id=email@mydomain.com): syntax error in Exim::expand_string argument: failed to open /home/mydomain/etc/mydomain.com/shadow for linear search: No such file or directory at /etc/exim.pl.local line 585.
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It looks like the shadow file is missing. How can I generate it and is there anything else to be done?

 

For my issue, cPanel support was able to resolve it using:

/scripts/mailperm --allaccounts --verbose

Not sure if it will fix in your case case though