boballoo,
http://www.mydomain.com/confirm_acco...709f1a1f17e619
Your URL contains repetitive information:
confirm_account.php and action=confirm
email=user@somedomain.com is likely already stored in your db
code=1f66e27c0b067dbd95709f1a1f17e619 is likely also stored in your db
Both email and code are likely to be unique in the db (especially the code).
With that in mind, your link should be http://www.mydomain.com/confirm/1f66...709f1a1f17e619 which, by mod_rewrite, would be converted simply by using:
Code:
RewriteEngine On
RewriteRule ^confirm/([a-z0-9]{32})$ confirm_account.php/action=confirm&code=$1 [L]
I'd like to think that you don't really need confirm in the URL so, if you DO need the email (isn't that already in your db?), then http://www.mydomain.com/1f66e27c0b06...somedomain.com would be processed by:
Code:
RewriteEngine On
RewriteRule ^([a-z0-9]{32})/([A-Za-z0-9\.\_]+@[a-z0-9\-]*(\.[a-z]{2,8}){1,2})$ confirm_account.php/action=confirm&email=$2code=$1 [L]
Sorry for that second atom - standard format validation for e-mail address
NOTE: I've assumed, by your example, that code will always be a 32 character string of lowercase and digits, ergo, ([a-z0-9]{32}).
If you want to learn about mod_rewrite, have a read of the article at datakoncepts.com/seo as it takes you from setting up Apache, testing that it works, building good regex, mod_rewrite's flags and provides a warning (and solution) for the problems generated with relative links. Yeah, it's tough to remember that your objective was to drain the swamp with all those alligators nipping at your backside. 
Regards,
DK
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