Split comma-separated cell in sheets while repeating other cell for all entries

I have a Sheet that looks like this:

╔═══════╦═════════════════════════════════════╦══╗
║  ID   ║                Users                ║  ║
╠═══════╬═════════════════════════════════════╬══╣
║ 12345 ║ bob@domain.com,su'uzan@domain.com   ║  ║
║ 99999 ║ steven@domain.com,rachel@domain.com ║  ║
╚═══════╩═════════════════════════════════════╩══╝

It's two column, one with an ID and one with comma-separated lists of emails. I need to look like this:

╔═══════╦════════════════════╦══╗
║  ID   ║       Users        ║  ║
╠═══════╬════════════════════╬══╣
║ 12345 ║ bob@domain.com     ║  ║
║ 12345 ║ su'uzan@domain.com ║  ║
║ 99999 ║ steven@domain.com  ║  ║
║ 99999 ║ rachel@domain.com  ║  ║
╚═══════╩════════════════════╩══╝

I've tried using pivot tables and some query operations but haven't been able to crack it. There's roughly 6,000 entries in the Sheet now. I also wasn't able to get anything from this question to work (I need something automatic, there's too much data to do manually.) This question also seems similar but is unanswered.