Per Sirsi Symphony's documentation (Step 11), the ILS returns a message to Connexion confirming the status of the exported record. Despite Connexion being capable of batch exporting to an ISL, Sirsi Symphony by default replies back with the status of each record. This cannot be disabled in Connexion.
Please contact Sirsi and inquire if this message can be disabled.
The following is the message Sirsi Symphony will send back to Connexion:
MARC Listener policy selected: NEW_ISBN
Symphony Catalog MARC Load 3.5.3 started on Tuesday, June 12, 2018. 2:15 PM
1 callnum(s) created.
1 bib record(s) read.
1 bib record(s) loaded.
Symphony Catalog MARC Load finished on Tuesday, June 12, 2018. 2:15 PM
Loaded record's catalog key: 123456
Title of loaded record: Test Title
MARC record successfully received.