Already.

Well, not for me:

# lsb_release -d
Description:	Fedora release 24 (Twenty Four)

# dnf info seamonkey
Last metadata expiration check: 0:00:20 ago on Wed Jan  4 08:30:52 2017.
Installed Packages
Name        : seamonkey
Arch        : x86_64
Epoch       : 0
Version     : 2.40
Release     : 6.fc24
Size        : 119 M
Repo        : @System
From repo   : @commandline
Summary     : Web browser, e-mail, news, IRC client, HTML editor
URL         : http://www.seamonkey-project.org
License     : MPLv2.0
Description : SeaMonkey is an all-in-one Internet application suite. It includes
            : a browser, mail/news client, IRC client, JavaScript debugger, and
            : a tool to inspect the DOM for web pages. It is derived from the
            : application formerly known as Mozilla Application Suite.

# dnf upgrade seamonkey
Last metadata expiration check: 0:00:25 ago on Wed Jan  4 08:30:52 2017.
Dependencies resolved.
Nothing to do.
Complete!

Sorry, but it cannot be updated in "one moment" -- normal update process requires at least 7 days in "testing" repository, as well as some time for some automatic testings etc. The maintainers of the package cannot speedup this anyway.

Try it again, now should be in stable updates.