[Dovecot] auth_username_chars question

[Linda Walsh]

I notice there is a space after the = in the default setting:
#auth_username_chars = 
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@
Is that space part of the syntax or required?  If not, does that mean 
'space'
is included in the default list of allowed characters?


If not, then is the space after the '=' required? -- If not, the implication
would seem to be that space is 'ignored'.   If that's the case, how does 
one include 'space' in the list of allowed characters?   Also, how does 
one include the "\" character in the list of allowed characters?

I.e. is anything accepted, literally, after the first non-space char after
the '=' sign?  I.e. any spaces after the first non-space char would be 
taken as valid character, and '\' would also be a literal character?


(not that'd I'd be using windows's clients or anything that would, on 
occasion, pass "DOMAINAME\user" as the calling user trying to log into
a 'user' account....or anything....*ahem*...)


Overrode it w/some hard-coded hacks, but would like dovecot to me more
robust and handle weird input and do the right thing with it (I know that's
always a challenging concept for some people, since the answers and ability
to arrive at 'correct' is always 'contextual', and so many people want 
absolute rules that apply all the time in all cases, but...I think thats 
a diagnosable psychological condition ;-) ).