Leaky epoxied sink drain
I think you probably know what you need to do... remove ALL that crap. Sloppy glues and putties never work with plumbing. It needs to be repaired the proper way.

The application of that epoxy has complicated this job. Your mission is to remove all the epoxy so you can see what you are dealing with.

The typical connection at that point: the plastic tube slides into a threaded 1 1/2" galvanized steel nipple (nipple is term for short pipe threaded both ends). A 1/1/2" slip-joint nut and washer on the plastic tube thread to the pipe to effect a seal.

There is a chance that:


the epoxy cannot be removed without complete destruction of all parts, this would require replacing everything
you can get the fittings apart only to find that the threads on the 1 1/2" nipple are damaged, this requires nipple replacement.
the galvanized nipple is so corroded it falls apart in your hands, leaving the threaded part in the wall; replace nipple after special operation to remove broken part still in the wall.


All the scenarios above (and many other things that could go wrong) can be remedied using special tool/procedures/parts/tricks. Taking pictures and bringing parts/pieces to a good plumbing shop will help tremendously. IMO you should not even waste your time at the big-box stores.

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