When passing Subscriber data for multiple Subscribers, should I put each Subscriber record on a different row? Or is it okay to include multiple Subscribers in one row?
There is a negligible difference in speed of import between passing multiple Subscribers in one row, or placing each on a different line.
For ease of troubleshooting, however, it's a good idea to put individual Subscriber data on separate lines. That way, if an error is returned in the FTP confirmation email, it will be easier to identify the culprit.