Home Resources Blog

When you setup a subscriber list in Campaign Monitor, you start with just an email address, and perhaps a name. If you’ve dug around a bit more, you might have noticed that you can add some more custom fields into each list, up to 50 in addition to the built-in name and email.

At their most basic, custom fields can be a great way to capture and store additional information about your subscribers. You might have a subscribe form on your website that also asks your visitors about their specific interests, and pass that information back to your own database.

Today we’ll mention some of the cooler ways you can make use of those 50 extra fields in your actual email campaigns.

Custom images

This is something that can make your emails look really varied but is actually quite simple. If you’d like to show different images to different subscribers, you can use the value of a custom field right inside an image link. For example, a car dealership could insert a photo of the specific model each customer has expressed interest in.

To make it happen, first you need the actual data in your custom field. In this example, a subscriber might have a field called ‘favcar‘ with a value of ‘datsunsunny‘. To turn that into a picture of said Datsun, your HTML would look like this:

<img src="http://www.yourwebsite.com/images/[favcar,fallback=genericcar].jpg" alt="A photo of your favourite car" width="150" height="100" cm_dontimportimage >

When our Datsun lover opens his copy of your email, the image path will become https://www.campaignmonitor.com/assets/uploads/datsunsunny.jpg. If a recipient has not specified a favorite car, then the fallback image will be shown instead. Note the cm_dontimportimage attribute there. That stops Campaign Monitor from trying to import the custom image along with all your other images. Instead, it is referenced from your own server.

There’s a lot of ways you might use custom images to make your emails even more targeted to each reader. Let us know if you have any ideas in the comments below.

Unique URLs

Do you have customer IDs which you would like to pass from your email through to your website? You could store those IDs in a custom field, and then insert them into a link as a parameter. Just like the custom images above, it’s a simple matter of using the correct tag inside the link.

<a href="http://www.yourwebsite.com/login.php?user=[id,fallback=]">Login to your account</a>

Custom permission reminders

One of the best ways to avoid spam complaints is to remind your readers how and where they signed up to your list. You might have a list that people always join via a single form, and, in that case it is very easy to write a simple permission reminder. On the other hand, you might sign people up online, in your store, at a tradeshow, on the street…that can be hard to explain in a simple way.

If you plan ahead, you can store the source of each sign up in a custom field, and then use that field to construct custom permission reminders. We’ve written about this before in How to personalize your permission reminders, so check out that post for more.

Add a personal connection

A very common use of email newsletters is for sales people to keep in touch with their customers and potential customers. Often all the sales people at a particular organisation are sending out the same newsletter. By using a custom field to store the name of the sales person for each subscriber, head office can send one campaign, but still have each email refer to the relevant contact for the recipient.

That might mean inserting the sales person’s name in the footer, their contact details or even using the custom images we’ve discussed above to add their photo. It’s a simple way to create a more valuable email.

Coupon codes

Sure you can send a campaign out to all your subscribers offering a discount with a single code, and that would work great, but what if you wanted to know exactly who responded, and who sent their code on to others? A custom field with a unique coupon code could be your answer. You insert the code into the email, and then you have a neat way of tracking back to find out which customer was most enthusiastic, who forwarded it on to their friends, and so on.

That’s just a few of the ways you could be using your custom fields to create more targeted and valuable email campaigns. Remember that every list can have up to 50 custom fields, and in each field you can have up to 250 characters of data.

  • Damien

    Wow, I’ve never thought of any of those kinds of applications – nice explanation.

  • James

    I know it’s quite boring but essential – In the last week we sent out a small campaign telling people their order wouldn’t be delivered due to the snow we’ve had in the UK. The content specified their order number with a link to a page to allow them to select an alternative delivery date for that specific order.

    We’ve also sent e-newsletters out to specific customers who have either ordered a particular product that we’ve had to do a recall on. Again, we’ve managed to target the content by showing their order number, plus the date that it was delivered on.

  • Dance Master Funk

    when did it snow?

  • Kev Charlton

    Recently I had a client who wanted a large table of share details to send to investors. If each cell had been a custom field it would have taken up about 30, which as we know isn’t possible in CM.

    I overcame it by creating an equation in excel that added together the data in table rows, outputting these as HTML. So one table row was one custom field. Worked a treat.

    Just thought I’d share!

  • Florian

    What would be the best way to send individual coupon codes using CM?
    I have to read in the codes from my online-store database into CM for instance, don’t I?
    How would this work?

    Cheers, Florian

  • Ben Brooks

    We have used the custom fields to provide login information and custom URLs for internal sites; for example for training or review time. We have also used them to insert a custom message into the mail.

  • Ed Skimin

    We use custom fields in CM to send individualized monthly preformance statistics to over 2,000 businesses with listing in our online local Business Directory. We have a small app that exports the data as an Excel comma seperated values file, we upload to CM and send the email.

    Thank you for saving us hours of work each month!

  • Jurgen

    hey CM, great article, but one question regarding the info below.

    Coupon codes
    “You insert the code into the email, and then you have a neat way of tracking back to find out which customer was most enthusiastic, who forwarded it on to their friends, and so on.”

    We have done this in the past with an HTML email and used customer specific codes, it works great, but the promo peram does not get passed through when the recipient forwards the email to a friend. It just shows up as the peram name ex. [promo].

    Have you changed the way custom fields are passed in a forwarded HTML email?

  • Jesh Barlow

    This post is like a favorite indie band getting some real radio play—it’s bittersweet. Sweet in that something loved for so long is finally getting ‘published’. Bitter in that it’s not as special anymore. Each of these techniques have been my company’s niche for several years and now it’s for everyone to see.

    I do like Kev’s approach to the 10 custom fields limit. That’s been a stinker for us in the past.

    Custom, one-to-one graphics from custom fields only start to make sense when you have more than, say, 5 creative versions relating to 5 list demographics. Otherwise, CM’s natural list segmentation / multiple sends combo make more sense. The benefit of using custom graphics (via the custom-field url injection method described in the post) is that you can send out different design versions to accompany relevant offers, news, and product info on a personal, one-to-one basis over a large scale without incurring multiple ‘send’ fees (i.e. $5).

    We launched a 400,000 email campaign to current customers featuring their last purchased product, appealed to the likelihood they’ve outgrown it, and presented a similar, slightly more expensive product they’d benefit from. We even used a custom url link technique like the one mentioned in this post (we call them personalized URLs) where each recipient clicks to a custom, trackable landing page continuing the individualized message, but with purchasing ability.

    There were over 50 products used in the campaign, and if we had sent it in 50 versioned ‘blasts’ using list segments / multiple templates rather than one, data-driven email template, we would have spent $250 in $5 send fees alone. It’s worth a little bit of time spent with set-up. Besides, you avoid the hassle of managing several jobs at once.

    There are so many applications for these techniques that really only our creativity and problem solving skills restrict them. I’m excited to see how CM’s clients have used custom fields for their own efforts.

  • Gavin

    While i love the user interface of CM, i really do think that it’s feature set is lacking when it comes to being able to send relevant emails. In camparison to other similar online ESPs (Email Service Providers), who offer such things as IF statements that enable entire blocks of content for particular groups, all that I can see on offer is 10 limited fields for data. At a point in email marketing when the recipient expects highly personalised/relevant content, and achieving high open rates often depends on this, CM should really start looking into adding this kind of functionality.

    Don’t get me wrong, I think CM is a great service though. Just my 2cents.

  • John O

    Great explanations and great functionality.

    Typo alert!

    Custom images:

    ……..For example, a **card** dealership could insert a photo of the specific model each customer has expressed interest in……

    Should that be “car” ?

  • David Greiner

    Thanks for sharing some awesome examples guys, keep them coming.

    @Kev, very cool approach, thanks for sharing.

    @Jurgen , you’ll be pleased to know that the promo parameter will now be passed on to whoever forwards the email to a friend. We basically forward an exact copy of the email your subscriber received, so the same custom field values will remain intact.

    @Jesh, we’ve seen you guys do some cool things with this approach, so thanks for sharing a few of them.

    @Gavin, thanks for the feature suggestion and feedback, appreciate it. We realize we could make this functionality much more complex, but to be honest have had little requests for it to date. I’ll notch your thoughts down now so it will be considered again in the future.

    @John O, thanks for the heads up, that’s been fixed.

  • Jassy

    Nice article. I will think about implementing it!

  • Florian


    How did you hook up CM with your shop-software?
    The only way to save individual coupon codes through custom fields is to first export that data from your shop-software and then import it into CM, right?
    There is no way to “dynamically link” CM with any external app’s database so any external data change is synced with CM – or is there?

    Cheers, Florian

  • Mathew Patterson

    Hey Florian,

    You can use the Campaign Monitor API to add custom field data to your subscribers. Some plugins do the work for you – see https://www.campaignmonitor.com/appstore/shopify/

  • Justin

    Not sure if I’m going to dish out the ooo’s and ahh’s like the others have here. To be perfectly honest the custom variables are a nice touch, but how they’re implemented and used in the code is elementary at best.

    What would make the variables actually useful and to create truly dynamic emails would be the use of conditionals (if/else statements)

    [if name=”bob”]
    do this html
    [if name=”becky”]
    do this html
    do this html

    Now THAT would be some fancy pants custom emails!

  • David Greiner

    Good call Justin, that WOULD be fancy pants. I’ve added your vote and it will definitely be considered.

  • GradskiPopusti

    Hi guy, you are the best. I want make dynamic newsletter. I have coupon site and I want when select cca 5 product send this product in my html template. Template have header and foot, in body I want sent 5 product with images, title, short description and link to product. Can I do this!? This newsletter send to all subsriber not personal. I would be eternally grateful :) If you now how, you can send me answer on my email srebic11@gmail.com or if someone knows of your followers.

  • Balthazar Simões

    Hi Gradski! I’m a little confused about whether you want to send them *same* content to all subscribers or *different* content to the various subscribers based on some criteria. If you could elaborate on that we’ll do our best to help!

This blog provides general information and discussion about email marketing and related subjects. The content provided in this blog ("Content”), should not be construed as and is not intended to constitute financial, legal or tax advice. You should seek the advice of professionals prior to acting upon any information contained in the Content. All Content is provided strictly “as is” and we make no warranty or representation of any kind regarding the Content.
Straight to your inbox

Get the best email and digital marketing content delivered.

Join 250,000 in-the-know marketers and get the latest marketing tips, tactics, and news right in your inbox.


See why 200,000 companies worldwide love Campaign Monitor.

From Australia to Zimbabwe, and everywhere in between, companies count on Campaign Monitor for email campaigns that boost the bottom line.

Get started for free