Subject lines… the easiest thing to write, the hardest thing to get right. There is just no single rule, tactic or word that works every time. Best practices sometimes fail and A/B testing can produce unexpected results.

Why is this? In simplest terms, being original keeps your subscribers on their toes and can spark in-actives into life. But if every subject line you write is surprising and original, your subscribers catch on and that lack of clarity has a negative effect.

Your email subject line. It’s an invitation, a front door, a salesperson, an ambassador. It’s important, to say the least. Here are 10 ½ tips to make your subject line Don Draper not Al Bundy, caviar not tofu — in a word: better.

There are dozens of sources, methods, and tactics to grow your email subscriber list, and we all know that not all of them are equally effective. Marketers have vague notions that organic list growth is best and paid acquisition of sources may yield lower quality subscribers, but there is little data available that gets at the validity of that assumption. I pulled some data from my own subscriber list to help throw some hard data into the mix.

It may seem self-serving for the long time CEO of an email agency to write about how to hire an agency. I certainly recognize that I am biased, but so is everyone. I will be as candid as possible. I also think that having worked for one for the world’s largest agency holding companies (NYSE:OMC — 75,000 employees, $16B annual revenue) for the last 14 years I have an uncommon perspective in the email space.

"While CASL seems well intended (What? You like spam so much that you won’t try to stop it? You must be a spammer!!!!) it’s a lousy piece of legislation. It’s akin to trying to kill a fly with a hammer. CASL is bad legislation for three simple reasons –"

For many of us in the email marketing profession, customer interaction equals B2C. Tens of billions of marketing emails are sent every day – to consumers. “Buy This!” “Check Out This Incredible Offer!” “Download the Last XYZ You’ll Ever Need!” … the thrust of most email campaigns is planned, designed, targeted, segmented, analyzed, measured, filtered, and executed with one purpose: drive consumers to a website and convince them to take action. So goes the eCommerce engine. And it works.

"When it comes to B2B email strategies, here’s 9 things that B2B marketers need to consider when preparing content for their campaigns."

"11 years ago, back in 2003, I founded a company called eDataSource, the world's first email intelligence company. As a result of the data eDS was collecting, I was able to clearly demonstrate, for the first time, the power of email to drive large spikes in traffic, across the board, and from an independent, 3rd party perspective. To say my jaw dropped open is an understatement."

"While mailing subscribers is indisputably important, there are several reasons why the importance of capturing email addresses has nothing to do with sending your new subscribers another email. And how you obtain those addresses has become critical."

If you take them aside in confidence and buy them a drink or two, most people working in email marketing will eventually admit there’s a hungry beast they have to deal with that is never full and always has an appetite for more. No matter how much or how often they feed it, it’s a bottomless pit.

"Every marketer knows that one of your greatest assets is your email list. In the '90s and early '00s, relatively little attention was paid to how you actually built that mailing list; the focus was on building the biggest mailing list possible, and mailing lists were often bought, sold, or shared. Nobody really thought about the concept of "permission", after all email was the closest thing to free advertising and marketing you could get, and if somebody had an email address, it was considered fair game."

"As email marketers we often get ‘in the weeds’ – focused on whether or not the opt-in box is checked (if you’re collecting email addresses from Canadians, CASL says it matters), agonizing over where the email sign-up call-to-action appears on your Website and trying to figure out if someone who offers to send your ‘sign up today’ message to 70 million qualified (according to them) prospects around the world is worth the $1,500 they’re going to charge you (hint: it’s likely not)."

"At FierceMarkets, a digital B2B publishing company, anywhere from 30%-80% of our email newsletter list growth comes from converting web visitors into subscribers. In this article, I’ll share what’s working for us, and hopefully you’ll be able to apply it to your organization."

"Getting end customers to go paperless is a focus for many companies and one of the easiest ways to do this is ask them to switch off paper for their bills and receive an electronic version instead."

"MarketingProfs started in 2001 and built up entirely organically a list of mailable email addresses that stands at over 300,000 today. In 2013, we deployed over 10 million such acquisition emails. So, having seen literally hundreds of advertisers trying thousands of offers has given us a great portal into what works in B2B email marketing."

"the single most important piece of data for a successful email program is the email address. You may think, "Hey Bob, thanks for that blinding glimpse into the obvious." The truth is, this is a piece of data that if often beyond the control of the email team to actually gather, as this is usually a function of the web team. "

"With leading marketing technologies already established and new technologies emerging on a seemingly daily basis, marketers are faced with making decisions about how to optimize and deliver results with their technologies of choice."

"Drip marketing describes a series of predesigned emails sent on a predetermined schedule geared toward education, branding, positioning, or selling of your product. Drip marketing emails are distributed to a broad audience; lead-nurturing emails are distributed to a specific segment."

"Triggered messaging is a rapidly growing part of marketing with extremely good ROI. It's about delivering business messages that are personalized and near-real time: often sent by email but increasingly by other channels such as within web pages. "

I got some great insights on responsive design and coding for non-techies from my colleague Luca Bellavita, a design and HTML manager for Alchemy Worx, which I shared in a recent ClickZ column. But one thing that’s been taking a lot of my head space lately is how and when to leverage responsive design and coding in unconventional ways.