Dovecot and other authentications for Exim

When using Dovecot authentication for Exim, which is relatively common, the current regex for catching authentication failures needs a small tweak. The current plain|login options are far too limiting and will only work in cases when only the Exim's rudimentary built-in authentication is used. There can be not only the dovecot_login authenticator name shown in this log example, but also dovecot_plain, ntlm, cram, cyrus, md5, and plenty of others. In fact many admins may opt for their own authentication labels, when setting up Exim. This is not something firmly given. I suggest modifying the failregex line for the authentication in the following way - simply just using "\w+" instead of "(plain|login)":

<pre>^%(pid)s \w+ authenticator failed for (\S+ )?\(\S+\) \[&lt;HOST&gt;\]: 535 Incorrect authentication data( \(set_id=.*\)|: \d+ Time\(s\))?\s*$</pre>