Start/notes.ini Parameters/SMTPDebugIO

SMTPDebugIO

SMTPDebugIO enables capturing of the complete bytes of the inbound SMTP conversation — i.e. not just the protocol commands (as with SMTPDebug), but including headers and mail body in the DATA block. This allows MIME, encoding, and body issues to be analyzed in detail.

Profile

Parameter
SMTPDebugIO
Component
Server (SMTP listener)
Category
Mail / Router (debug)
Available since
9.0.x (per KB0032184)
Default
0 (disabled)
Values
0, 1, 2, 3, 4
Additionally requires
debug_outfile=<path/file.txt>
Output destination
File from debug_outfile (not log.nsf)

Detail levels

Value
Meaning
0
I/O logging disabled (default)
1
Minimal I/O logging (connection events)
2
Info logging with byte counts
3
Verbose: sent/received plain-text data
4
Complete byte capture incl. mail body and headers
The exact levels vary slightly by Domino version; level 4 is the most verbose per KB0032184 and contains the complete DATA content.

Description

SMTPDebugIO is the finest inbound debug level at the Domino SMTP listener. Where SMTPDebug captures the protocol commands (EHLO, MAIL FROM, RCPT TO, DATA, ...) and response codes, SMTPDebugIO additionally logs the raw data on the TCP connection — i.e. headers, MIME boundaries, base64/QP encoding and possibly the complete message body.
Like SMTPDebug, SMTPDebugIO mandatorily requires debug_outfile, since the output does not land in log.nsf but in the configured text file.

Examples

Full byte capture (level 4):
SMTPDebugIO=4
debug_outfile=C:\\Domino\\Logs\\smtp_io.txt
Combination with SMTPDebug for comprehensive diagnostics:
SMTPDebug=3
SMTPDebugIO=4
debug_outfile=/local/notesdata/IBM_TECHNICAL_SUPPORT/smtp_full.txt
Dynamically via the server console:
set config SMTPDebugIO=4
set config debug_outfile=C:\\Domino\\Logs\\smtp_io.txt
tell smtp quit
load smtp
Deactivate:
set config SMTPDebugIO=0
tell smtp quit
load smtp

Notes

  • Very large files – At level 4, every received mail is written completely into the log file. The log file grows accordingly fast; only enable briefly.
  • Privacy / compliance – Since the complete mail content (including attachments in MIME encoding) is logged, an SMTPDebugIO=4 capture contains personally identifiable data under the GDPR. Protect or promptly delete the log file.
  • Attachments – Attachments appear base64-encoded. For analysis, extract and decode if necessary.
  • Activation order – First set debug_outfile, then SMTPDebugIO, otherwise the first data is lost.
  • Combination – Often activated together with SMTPDebug; for support cases, KB0032184 recommends combining both parameters.

Sources (HCL Product Documentation)