After an email campaign has been sent, is there a way to update the hyperlinks in the email?

You can redirect the link to a Marketo landing page and the Redirect a Landing Page help article explains how.  If you are sending them to one of your website pages, you should be able to get your webmaster to help you set up a redirect to the proper page.

I suppose the link in the email would have needed to originally go to a Marketo landing page? If not, am I out of options?

Brigite, no  the link in the email doesn't have to originally go to a Marketo landing page.  It can point to your website.  I do redirects all the time. Sometimes the wrong link gets printed on our print publication and I have to set up a 301 redirect right away. 

Thanks all!
But in this case the email has already gone out with a link to a 3rd party website. Is there a way to update the link in an email that has already gone out so that it points to the correct URL? It seems that the solutions mentioned require the original message to have a link that points to a page/link that I can control. In this case I don't.

I was hoping that since Marketo creates redirects for all links in an email anyway--there may be a way to update that redirect after the email has been sent.