Hotfix R097883: Integration_x64_15.20_HF094 resolves this issue by using the appropriate Metadata property.
The metadata property Journal Envelope Sender/On-Behalf-Of Address (Exchange only) should be configured as directed in the Notes section below.
1. Download and extract the required .zip files.
2. Apply the hotfix.
2.1. Apply Integration_x64_15.20_HF094.msp to all 64-bit machines where an IBM Content Collector Integration Agent is deployed.