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Filled-up applications must be reached (to) the Management by / on or before July 25, 2008.

Do "by" and "on or before" express the same meaning? And is the preposition "to" necessary here? Thanks
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"to" is not needed, in fact is incorrect.

by = no later than this date
on = on this date / before = before this date. "on or before" = you have up to this date to get this application in.

I would say they are virtually the same in intent.
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Thanks Feebs
Abil Filled-up applications must be reached (to) the Management by / on or before July 25, 2008.
Do "by" and "on or before" express the same meaning? And is the preposition "to" necessary here? Thanks

on or before 20 Sept 2019, the acceptance for the invitation I see and accept for the application confirmation email today, is that accepted!

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