Is encoding email links in characters entities still useful?

Many sites advise to encode email links in characters entities, to prevent robots from getting your contact email address.

You get something like :

<a href="&#109;&#97;&#105;&#108;&#116;&#111;&a开发者_高级运维mp;#58;&#109;&#121;&#101;&#109;&#97;&#105;&#108;&#64;&#103;&#111;&#111;&#103;&#108;&#101;&#46;&#99;&#111;&#109;">&#109;&#121;&#101;&#109;&#97;&#105;&#108;&#64;&#103;&#111;&#111;&#103;&#108;&#101;&#46;&#99;&#111;&#109;</a>  

Is it still useful, or do all robots understand this nowadays (2010) ?

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That's not unicode, it's character entities. Probably there are new robots getting written every day, and not all of those will understand the entities, but it is probably a tiny percentage of the robots out there today.

An interesting experiment would be to create two junk email addresses, encode one of them as entities and leave the other along on the same webpage and see whether there is much difference in the spam received by the two addresses.