Moreover in those days. Ewald supposes that the circumstances here related (Nehemiah 6:17-19) were subsequent to the completion of the wall; but the expression "in those days" seems rather to throw back the events into the time during which the wall was in building.
The passage is a sort of explanatory note, showing us how Tobiah came to be able to raise those intrigues inside Jerusalem which have been mentioned in Nehemiah 6:12-14. And the letters of Tobiah came unto them.
Rather, "and many were the letters of Tobiah which came to them."