The -d11.1 (a.k.a. -d11) debugging switch is used to trace message delivery. It must be run with the -v command-line switch, or no output will be produced.

First, for each delivery agent the following is printed:

openmailer: argv

Here, argv is the A= array for the delivery agent, with macros expanded and printed.

Second, the status of remote hosts is cached internally. Before connecting to a remote host, sendmail checks its cache to see whether that host is down. If it is, it skips connecting to that host. If the -d11.1 debugging switch is also specified, the status of the down host is printed as:

openmailer: output of mci_dump( ) here

The output of mci_dump( ) looks like this:

MCI@memaddr: flags=mci_flags<flag,flag,...>,
errno=mci_errno, herrno=mci_herrno, exitstat=mci_exitstat, state=mci_state, pid=mci_pid,
maxsize=mci_maxsize, phase=mci_phase, mailer=mci_mailer,
status=mci_status, rstatus=mci+rstatus,
host=mci_host, lastuse=mci_lastuse

The meaning of each mci_ item in this output is described in Table 16-8.

Table 16-9 shows what the individual flag bits in mci_flags mean, and the human-readable flags text that corresponds to each bit. Those text items are shown with the leading source MCIF_ prefix removed.

Table 16-9. The meaning of mci_flags hexadecimal values

Name printed	Hex value	Meaning
VALID	0x00000001	This entry is valid
TEMP	0x00000002	Don't cache this connection (prior to V8.12)
CACHED	0x00000004	This connection is currently in open cache
ESMTP	0x00000008	This host speaks ESMTP
EXPN	0x00000010	EXPN command supported
SIZE	0x00000020	SIZE option supported
8BITMIME	0x00000040	BODY=8BITMIME supported
7BIT	0x00000080	Strip this message to 7 bits
MULTSTAT	0x00000100	MAIL11V3: handles MULT status (prior to V8.12)
INHEADER	0x00000200	Currently outputting header
CVT8TO7	0x00000400	Convert from 8 to 7 bits
DSN	0x00000800	DSN extension supported
8BITOK	0x00001000	OK to send 8-bit characters
CVT7TO8	0x00002000	Convert from 7 to 8 bits
INMIME	0x00004000	Currently reading MIME header
AUTH	0x00008000	ESMTP AUTH= is supported (V8.10 and above)
AUTHACT	0x00010000	SASL (AUTH) is active (V8.10 and above)
ENHSTAT	0x00020000	ENHANCEDSTATUSCODES SMTP extension supported (V8.10 and above)
PIPELINED	0x00040000	PIPELINING SMTP extension supported (V8.12 and above)
TLS	0x00100000	STARTTLS SMTP extension supported (V8.12 and above)
TLSACT	0x00200000	STARTTLS is active (V8.12 and above)
DLVR_BY	0x00400000	DELIVERBY SMTP extension supported (V8.12 and above)
HELO	0x00800000	Sending sendmail used HELO, so ignore extensions (V8.12 and above)
ONLY_EHLO	0x10000000	Use only EHLO when establishing a connection (V8.12 and above)

After checking to see whether the host is down, sendmail attempts to connect to it for network SMTP mail. If that connect fails, the -d11.1 debugging switch causes the following to be printed:

openmailer: makeconnection => stat=exitstatus, errno=errno

Here, exitstatus is a numerical representation of the reason for the failure, as documented in <sysexits.h>, and errno is the system-level reason for the error, as documented in <errno.h>.

Other errors, such as failure to establish a pipe(2), or failure to fork(2), cause the following to be printed:

openmailer: NULL

This message (although it contains no information) signals that a more descriptive error message was logged with syslog(3) (Section 14.3).