Unbuscribe link problem

We have sent out an mailshot to around 65k recipients, turns out the unsubscribe link has an error :-(

When the unsubscribe link is clicked you get an 404 error, i have checked the URL and it turn sout its missing the colon after http, i.e.

http//marketing..... rather than http://marketing...

Not sure what needs to be done to fix this for future campaigns but more importantly is there a way to fix the link for the 65k or some mails already sent.

You cannot change the content of the emails that went out, so that link is broken for good.
In future, there is a reason why we have [UNSUBSCRIBE_URL] and [UNSUBSCRIBE_LINK]
These act different, UNSUBSCRIBE_URL as the name says, generates a URL, which means that if you place it using the editor, you have to select "other" as the link protocol because the tag itself will contain the protocol, so this is how you correctly add it:
Screenshot 2019-04-17 12.56.14.png
Which in html will look like:
Screenshot 2019-04-17 12.57.03.png
So this is the correct way to add this.

If you do this in the editor:
Screenshot 2019-04-17 12.58.02.png
Then the html will look like:
Screenshot 2019-04-17 12.58.42.png
So unchanged. But later when the email is sent, mailwizz will transform this tag into
<a href="[UNSUBSCRIBE_URL]">Unsubscribe</a>

So it's important to use only one of them and know how to use it. If in doubt, just use [UNSUBSCRIBE_LINK] directly in the editor as text, do not link it or anything, and later mailwizz will transform it properly in a html link.

As always, test your campaigns to a test list before actual sending.