5 Ways to Aggressively Grow Your Newsletter Subscribers Simply placing an opt-in form on your website isn't enough to build a large subscriber list.

Email is one of the most effective forms of digital marketing and an essential component of every campaign. A great way to build your email list is to offer a newsletter.

Simply placing an opt-in form on your website isn't enough to build a large subscriber list. Sure, you will get the occasional subscriber here and there, but if you want to aggressively grow your list consider these five options.

1. Include an opt-in form after each blog post.

By placing an opt-in form at the bottom of each blog post you are catching the visitor at the perfect time -- right after they finish reading your content. If your content provided value the visitor will be more willing to hand over his or her email address to continue engaging with your brand.

Related: Email Subject Lines Can Really Suck. Here's How to Make Yours Better.

If your website is built using WordPress there are several free plugins that allow you to create several customizable styles of opt-in forms and integrate them with your email marketing service. Optin Forms and WP Conversion Boxes are two great options.

2. Promote your newsletter via social media.

Every business should have a social media presence, and this is a great audience to attract newsletter subscribers from. Is every single follower and fan that is socially connected to your business already subscribed to your newsletter? That is highly unlikely, making this an easy way to add new subscribers.

If someone has "Liked" your Facebook page or is following your Twitter account then there is already an established relationship. They are obviously interested in your brand, so encourage them to join your newsletter by sending out frequent posts welcoming them to subscribe by highlighting the benefits of your newsletter.

3. Run contests and giveaways.

What is one thing the majority of people can't pass up? Something for free. It doesn't even have to be some outrageous giveaway in terms of monetary value. In fact, your own products or service is often the best giveaway.

Create a contest and offer a free trial, free service or free product -- and to be entered into the contest require that the individual subscribes to your newsletter and shares the contest on Twitter or Facebook. So you gain a new subscriber and you also get additional exposure across social media, which can potentially attract more subscribers and more social promoters. The right contest can become viral quickly, delivering a huge influx of email subscribers.

Related: 5 Do's and Don'ts For Creating Effective Email Lists

4. Use an exit-intent pop-up offer.

There will be some people that just don't complete your website forms, even if they are placed right after your blog content. While aggressive, an exit pop up can help convert traffic into blog subscribers. Rather than using a pop up that fires when the page loads or after a specific period of time, opt for one that uses exit intent technology, only displaying when it detects that the visitor is about to leave.

Bounce Exchange, the pioneer of converting abandoning traffic, is behind some of the most aggressive and successful exit conversion campaigns. In fact, I have witnessed enough successful campaigns run by Bounce Exchange that my company, Market Domination Media, has engaged it to create and manage campaigns designed to increase our newsletter subscribers.

5. Create Twitter lead generation cards.

This is one of my favorite ways to build highly targeted email lists for our clients. Twitter lead generation cards allow you to create an offer and collect email addresses in a single click. What's the best part? You know the email address is valid because Twitter passes the email address that the user has confirmed and uses in his or her profile.

Twitter ads have incredible targeting options, which allows you to only present your newsletter offer to prospects that match your target criteria. You have to pay for each email collected, but for businesses that really want to grow their subscriber list fast this is a great option.

Do you have any additional tips for rapid newsletter subscriber growth? If so, share them in the comments section below.

Related: Here Are 6 Data-Backed Tricks for Getting Your Sales Emails Opened