> It is*critical* you follow canning safety guidelines (but you surely already know that). I once made a batch of tomatoes that caused several of us (we were at a cookout) to become quite ill, in hindsight we were very lucky that it was not worse...
What was the root cause?
It's pretty hard to screw up tomatoes, as they are acidic.
(pressure canner isn't needed). Boiling water bath works fine.