Sendmail on FreeBSD 14, gmail problem

I've got a FreeBSD 14 host running sendmail from packages that works perfectly
otherwise but can't be persuaded to communicate with gmail:
(reason: 550-5.7.26 This mail has been blocked because the sender is unauthenticated.)

I've tried to follow the directions in the Handbook, but they assume a self-hosting
configuration with /usr/src available and so require some actions not available and,
I think, unnecessary.

Sendmail presently reports
bob@www:~ % sendmail -d0.1
Version 8.17.1
 Compiled with: DNSMAP IPV6_FULL LOG MAP_REGEX MATCHGECOS MILTER
MIME7TO8 MIME8TO7 NAMED_BIND NETINET NETINET6 NETUNIX NEWDB NIS
PIPELINING SCANF STARTTLS TCPWRAPPERS TLS_EC TLS_VRFY_PER_CTX
USERDB XDEBUG

============ SYSTEM IDENTITY (after readcf) ============
      (short domain name) $w = www
  (canonical domain name) $j = www.zefox.net
         (subdomain name) $m = zefox.net
              (node name) $k = www.zefox.net
========================================================

Recipient names must be specified

The reference to TLS makes me think the binary already supports authentication.

/etc/make.conf contains
bob@www:~ % more /etc/make.conf
SENDMAIL_CFLAGS=-I/usr/local/include/sasl -DSASL
SENDMAIL_LDADD=/usr/local/lib/libsasl2.so

/etc/mail/freebsd.mc contains
# more freebsd.mc
divert(-1)
dnl set SASL options
TRUST_AUTH_MECH(`GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnl
define(`confAUTH_MECHANISMS', `GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnl
#
# Copyright (c) 1983 Eric P. Allman
# Copyright (c) 1988, 1993
.....

It looks like saslauthd is running:
# ps -aux | grep -i sas
root     76778   0.0  0.1  19708  1340  -  Is    6Apr24      0:00.01 /usr/local/sbin/saslauthd -a pam
root     76779   0.0  0.1  19708  1332  -  I     6Apr24      0:00.00 /usr/local/sbin/saslauthd -a pam
root     76780   0.0  0.1  19708  1332  -  I     6Apr24      0:00.00 /usr/local/sbin/saslauthd -a pam
root     76781   0.0  0.1  19708  1332  -  I     6Apr24      0:00.00 /usr/local/sbin/saslauthd -a pam
root     76782   0.0  0.1  19708  1332  -  I     6Apr24      0:00.00 /usr/local/sbin/saslauthd -a pam
root     34044   0.0  0.2  12704  1928  0  S+   09:41        0:00.01 grep -i sas

Is there a FreeBSD expert out there who can tell me what I've missed?

Thanks for reading,

bob prohaska