From JabberWiki

MD5 hash support

Clients differ in whether they send the 'hash' attribute when sending a file, and whether they check the hash after downloading a file. This is an attempt at summarizing the situation; feel free to extend and correct it.

Sends, but doesn't check

• jabber.el (since 0.7.1, assuming it finds such a tool in the path)

Neither sends nor checks

• Tkabber (SVN trunk of 2007-05-08)
• Psi (SVN trunk of 2007-05-08)
• Gajim (SVN trunk of 2007-05-08)