As a reverse mortgage professional, your best method for expanding your client base is to secure referrals not only from friends, but also Realtors, financial advisors, lawyers and other professional sources close to you. But how can you do this quickly and cheaply? By staying top-of-mind with your referral sources through email marketing.

Email marketing is a proven and cost-effective method for many sales professionals. According to a 2013 Direct Marketing Association study, email marketing produces an average return of $43 for every $1 spent. But in order to see such a return, your campaign must be done right. Purchasing email lists and spamming people won’t get you results.

The right way to approach email marketing is to use it to follow up with the people who already know, like and trust you, such as past clients, prospects, referral sources and professional acquaintances. A good campaign aims to maintain and accelerate your relationships with your contacts. One great way to do this is to send personalized birthday greetings.

I recommend using Constant Contact as your email service provider to initiate email campaigns, although there are similar solutions in the market that could work just as well.

Here’s what you need to do to launch an effective birthday email campaign:

Step 1 Get a spreadsheet of email addresses together, including name, email and birthday. I suggest building your list using the contacts in your Outlook or Gmail, your stash of business cards and your LinkedIn contacts.

Step 2 Delete the contacts you don’t really know. If you got an email from that person, would you immediately recognize it? If not, delete it.

Step 3 Start digging for birthday information. If you use Gmail and your prospect listed their birthday on Google Plus, then their birthday will automatically be added when you export your contact list. You might also find birthday information on Facebook and LinkedIn. Reach out to people individually to fill in the gaps.

Step 4 Import the spreadsheet into your Constant Contact account (or whatever service you are using).

Step 5 If you are using Constant Contact, click on the create button and use their template to design your campaign. (Note: Do not take this opportunity to pitch. Just wish your contact a happy birthday and leave it at that!) The great thing about this is that you set it up once and whenever a birthday comes up, an email is sent automatically.

Once you have honed your contact list and solidified your relationships through birthday greetings, take it to the next level by reminding them of your services. Focus on generating reverse-specific content. Write a blog post or create a video that offers insight into how the product can be useful. Don’t overthink it.

At the end of your message, leave a phone number and email address that your prospects and referral partners can use to schedule an appointment. Then, create a landing page where your contacts can access your content. Most email providers like Constant Contact have free landing page tools that you can use.

Send an email to your contacts that says something like, “Hey, I’ve put together a report about reverse mortgages and the work that I do, and I thought you might be interested.” Include a link to your landing page. It’s important to give your contacts the option to view your report by suggesting they click on the link. Do not just send them the report. This way, you can view traffic results to gauge the level of interest. Those who click on the link are now part of your new list.

Send follow-up emails to this new list. Continue to build value by creating new content. Invite them to webinars or live events. Ask them if they want to set an appointment with you and move them into your sales process. I guarantee that if you take this seriously and do it, you will enhance your referral base and better your business.