You  need "@myht.org" domain setting to GMail if use localhost SMTP.
$wgPasswordSender = "no-reply@myht.org";

You need set your contact address in Reply-To: email field.

Or other method. You can do full SMTP settings to outer service(SMTP).
see detail mediawiki document. (I don't know well)
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安冨　伸浩 (マイサイト管理人)