Sendmail & Valid users

Matthew Seaman m.seaman at
Fri May 2 12:21:39 PDT 2003

On Fri, May 02, 2003 at 11:55:34AM -0700, Mike Hogsett wrote:

> I have a question regarding sendmail and this list may be able to point me
> in the right direction.
> What I want is to be able to verify the address in the "MAIL FROM:" during
> the SMTP transaction for domains that this sendmail is responsible for.
> If they are claiming to be within our domain(s) then the address in "MAIL
> FROM:" should be a valid recipient.

The standard mechanism use to control this sort of thing is the access
DB (/etc/mail/access) -- take a look at

for a good introduction.  There's more that can go into the access
database than is discussed in that page: the canonical reference is
the /usr/share/sendmail/cf/README file.

Now, the access db is usually keyed off the domainname part of an
address: you can do some filtering on whole addresses but it isn't
really a general solution.  If you need finer grained control than the
access DB can give you, you should look into using the sendmail AUTH

or even the STARTTLS support:



Dr Matthew J Seaman MA, D.Phil.                       26 The Paddocks
                                                      Savill Way
PGP:         Marlow
Tel: +44 1628 476614                                  Bucks., SL7 1TH UK
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