Question: How do I verify if a string of characters is a valid e-mail address?

First, you can only be sure about the second half of the e-mail address (the domain), as (in order to protect the anonymity of their users) many e-mail servers don’t give immediate responses when checked to see if the first part of the e-mail address is valid (although some will send a bounce notification at a later date, once an e-mail has been attempted).

Second, you can only TRULY verify if the domain address is accurate if the testing application has internet access.

So, without making a DNS call (or before), you can’t be absolutely sure that the user or the domain actually exists, and can never be sure if the user (and therefore the email) is an actual e-mail address.

But you can check to see if the format is valid using a regular expression. And this is where things get REALLY tricky, as how restrictive you want to be in your filtering depends on you, and while there is a defined standard, simply adhering to that standard may exclude e-mail addresses that are in use.

It seems that the most common regular expression that is suggest on the web is the following:

^[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$

This will cover ALMOST all e-mail address you will run into, and will exclude obnoxious e-mails like badpirate@gmail.com.nospam

However, it will exclude a few e-mail addresses that are in use (but are probably being excluded and having trouble in lots of places:

• kevin@yesthistldexists.museum – Yes .museum is a valid Top Level Domain
• kevin@kevin@logichigh.com – Yes the current e-mail RFC doesn’t allow this type of e-mail address HOWEVER older RFC’s did, and so there may be some folks still using this format (and not being able to use this format in lots of other places)
• ??@??web.jp – International characters in domains and user names are already being normalized to ascii friendly code by browsers and e-mail clients, so they are being used regularly, however if you are checking before that normalization occurs, these sorts of e-mail addresses will get tossed

Therefore, I’ve also written a super lax e-mail format checker that will catch all scenarios. This reg ex would probably be best used if you plan on checking to see if the domain exists after checking to see if the format loosely matches SOME format that COULD be in use

^.+@.+\.[A-Za-z]{2}[A-Za-z]*$

Finally, if you’d like to implement this in cocoa code:

BOOL NSStringIsValidEmail(NSString *checkString)
{
	NString *stricterFilterString = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
	NSString *laxString = @".+@.+\.[A-Za-z]{2}[A-Za-z]*";
	NSString *emailRegex = stricterFilter ? stricterFilterString : laxString;
	NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
	return [emailTest evaluateWithObject:checkString];
}

Coming soon!

Arrr… For the truly compulsive GoWalla user.  This here application will perform an ever growing spiral search from your current location and will find any booty (items) you have not collected yet in all nearby locations.  Yarr.. and it can be fine tuned to even help you lower the issue numbers of your existing collected items.
Why would you want to do all of this?  Because you are compulsive.  And gotta have them all.
Why am I charging $5??

1. This tool is incredibly effective at helping you find rare items.  Rare items that I might also need.  Rare items that other users of the application would just as soon hope that YOU never find.  By making it cost as much as a draft beer, I can assure that only the devoted pirates find the treasure.
2. The Gowalla API be a shifty one.  Gowalla changes the way their backend works ALL THE TIME, and with NO WARNING.  I could do this application for free… but the upkeep would soon make it not worth the effort to update, and it would be a free broken application.  By charging a few bucks, I can make it worth my time to deal with the GoWalla headache.
3. I’m a pirate.  Yarr.  Need dub-loons to buy rum.

So a big part of my day is going through my Google Reader news feed and I have a handful of shows that I subscribe to on Hulu, plus movies that I watch on Netflix, feeds I read on facebook and twitter, the occasional bored streak Stumbling around the internet, subscriptions on youtube to check, and a host of other things I’m sure I’m not thinking of right now.  So I’ve decided, that starting Thursday morning and going for a week (through April 1st), I’m cutting myself off.  The Netflix will sit unopened, the Hulu and RSS feeds will just have to pile up.  Until the end of this month, I will cease to be a consumer of content, and will dedicate the extra time to producing and enjoying.

Retweet this if you’d like to join my fast.  But don’t expect me to read your tweet and respond

Kevin OUT!

I made a tool that should be useful to people who play GoWalla too much.  Currently, it has two functions:

• GCD – Gowalla Compulsive Disorder – Gives you a score based on how many items you’ve collected and how cool (low number issue) they are.
• Search Oahu – Searches ALL of Oahu and your friends inventories for items that you need in your collection and tells you where to find them.

Enjoy.

Just finished another iPhone Application, and you can find it in the Apple Store for free starting today!  Start getting great savings around Hawaii using this Malama Card Application built for Kamehameha Schools.  And keep your ears open for more great applications from Logic High Software!

Fast Tube by Casper

Hey everybody, I’ve got a new geo-location based game coming out very soon that I’d like to beta test a little bit before it’s launch.

Specifically I’m looking for iPhone 2G, 3G and 3GS owners, preferably in the Oahu area as the game is multi-player and depends on having friends to battle with, however if you have a few friends who are also iPhone owners and want to test it out in your area then that is dandy as well.

Sign up for the beta tester mailing list to be a tester

Logic High Blog has been having some trouble recently, but now that I’ve got everything strapped down, and re-situated at a rocking new host all the old links have been restored and you can expect new posts and information here, for everything that has to do with Kevin Lohman, BadPirate, or Logic High Software.

Sign the petition – Slashdot it

The new iPhone 3GS was announced today, and many of it’s new features were confirmed by Apple.  And AT&T won’t be supporting some of these new features, I’d like to explain what, why, and what we as consumers can do to prevent it. One of these great new features is tethering, and will be offered in many countries by a variety of carriers, but… AT&T wasn’t even stated as being one of the companies PLANNING a launch.  WHY?  Your network supports it, the phone now supports it… Another one of these great new features was MMS, and while it is being offered on “Twenty-nine carriers in 76 countries” guess which country isn’t going to be one of them? AT&T is the only carrier of the iPhone in the US, and despite offering it for many of their other video/photo capable phones, iPhones have been left out and forced to use a very awkward and painful system to view their MMS’s (Open SMS, copy down long random user name and long random password, and then, because the link isn’t even often properly clickable, copy down the link, manually enter link into iPhone or computer browser, and at the corresponding web page manually enter both the long user name and the long password.  If there were no typo’s in this process you’ll get a crappy miniturized version of the original content sent to you).  Can’t blame Apple, the phone demonstrated it was quite capable of displaying photos and videos, even with the old model.  And now that sending MMS is integrated into the new operating system, there remains no excuse whatsoever.  But AT&T is in no hurry, stating no support until late summer because… drumroll: They have to remove the Opt-Out codes for all the iPhones in the system. So they have a little toggling to do in their database.  Should this process take 2-4 months?  No.  But it will.  Because there is no market pressure for them to do so.  AT&T set it up that way.

Contracts

What about all the screaming customers?  Don’t they represent market pressure?  Not really.  First lets look at the group, currently the only AT&T customers who are holding phones that can support MMS, and will support tethering who won’t be able to use these features are iPhone users.  Blackberry users on AT&T are currently enjoying BOTH of these features.  So the only customers screaming are iPhone users.  And AT&T has us 2 ways:

1. Contract – Most iPhone users are in a 2 year contract, that isn’t up and won’t be up for a while, additionally new hardware purchases, lost broken phones (no insurance offered), price plan changes, etc. all extend your contract.  It’s a zero sum game.
2. Hardware – for those of us who dutifully make sure not to change our price plan, own the oldest iPhone hardware, and refuse cheaper upgrade plans, the contract can’t hold us.  But AT&T’s current exclusivity agreement for the iPhone can.  Sure you can hack your phone, and put it on T-mobile, but you won’t find MMS or tethering there because they can’t officially support it until the agreement runs out.  You’ve made a large investment in the cost of your phone, in money, applications, learning curve, etc, and this inertia is enough to keep most customers with AT&T.  Until the features and screaming make it so we’re better off going through the hastle of switching carriers, buying another phone and learning it.  They’ve got us.

Monopoly Power

A quick economics lesson: So, AT&T has a large group of customers (iPhone users) who have a large barrier to exit (the requirements for excercising monopoly power) as well as lack of available substitutes (for many of us iPhone users, there is no substitute).  These ingredients allow for the excersing of monopoly power.  What does this mean exactly?  In a perfectly competitive economy every business is forced to take the price of the market and keep their features comparible in order to be competitive.  This price is where the marginal cost (the cost of producing one more unit of product) is equivalent to the marginal profit for selling that unit (What the consumers are willing to pay), this ratio provides no excess profit to the corporation, and leaves all that extra value with the consumer.  Maybe you were willing to pay more, but because of competition you didn’t have to. Monopoly power (whether a true monopoly or a partial monopoly) allows companies to move closer to their ideal selling location, the point at which marginal profit (The profit made for selling an additional unit) is greatest.  They may sell less units, but at a higher price and a more economic cost / revenue ratio.  The consumers end up paying much more, and they lose the advantage they have in a competitive environment.  At the moment, while AT&T would gain customers and remain profitable if they had more reasonable price plans (like not charging extra for SMS, or better data prices) they have no incentive to (from a purely profit standpoint) as they can make MORE money by charging their existing customers more. The same holds true for features.  New features, like MMS / Tethering cost money to implement, and while doing so might bring them more customers (and likely they would still remain profitable), their number crunchers have clearly decided that the costs won’t outweight the profits. Basically, there is a slider, you can choose straight profit $$$ or you can give some of your profit back to the customer in exchange for loyalty and market share.

Comparative Profit Margins

Here is a list of the major wireless companies and their operating margins.  In a particular market the players with a higher percentage here are either operating much more efficiently then their competitors, or are taking more customer surplus (good will).  Looking at these figures you might guess that AT&T has the largest subscriber base, when actually Verizon does.  Verizon also happens to rank up near the top in customer satisfaction among us carriers.  T-Mobile, which also has a really high profit margin is the other company that ranks up with Verizon on customer satisfaction, but their relative user base is also much smaller then AT&T. So AT&T charges more money, serves less customers, or has a lower customer satisfaction rating then it’s competitors.  It’s their business model.  And it’s raking in some great profits.  But it doesn’t have to be that way.

Alternative

It’s probably too late to save the iPhone exclusivity, Apple does not have a history of tolerating poor service from it’s partners, and based on the zingers during todays Keynote, they won’t be likely to re-up the exclusive contract.  But AT&T can still bring it back.  By providing a more customer friendly model, the services that the customers (and partners) are demanding, and they’ll keep most of us, but commitment needs to be shown.  Not just a rollout at the expected late date, but an immediate, public and effective effort (even if costly) to surprise us all with a simultaneous feature release date.  The positive press, customer loyalty returned, and in the long term, profits will outweigh any other business plan.

Action

Please tell AT&T that when the option comes to leave, you’ll be walking.  But also, let them know that if they commit themselves to improving the customer experience that you will stay.  By doing so we may affect change.

Sign the petition – Slashdot it

I was looking around wordpress.com today because for SOME easy way to make posts with more entertaining fonts and styles.  Also, it needed to be easy enough for a end using client to use.  There was a short discussion, and a corresponding FAQ on the wordpress.com website, but all the options they offered were expensive, difficult for non web programmers, or intermittent (Pasting from word only seemed to work sometimes, and requires you to use M$oft products).

I was thinking, wouldn’t it be nice if you could just use the editor in g-mail.  And as it turns out:

That Works Perfectly.

Right down to the emoticons.  It doesn’t have EVERY font available, but only the ones that tend to be safe for use in all browsers.  In order to use it, type your intitial wordpress post as an e-mail, then when you are finished, copy the whole thing, and paste it into a wordpress entry. Once you are done, you can use the wordpress.com editor to make any changes (like adding images) that you weren’t able to do in the g-mail editor.  WHOOPIE!

I hope this works for your problem as well as it worked for mine.  Happy blogging.