When is the best day of the week to send an email? What is the best size for an image in emails?

Our Email Marketing Best Practices guide has answers to these questions and more.

Download a printable version

Be strategic about your email list. Don’t blast the entire world with information that doesn’t relate to them.

Your query or list should only include those who will directly benefit from the information in your email. It’s better to send a message to ten people who all open the email than to send to 100 people and annoy 90 of them.

eComm Data

Need to know what data to use to build an email list? Check out the data section for more information about eComm data.

The meat and bones of your campaign is your message. It must be engaging, easy-to-read and informative. Learn more here to make your message pop! 

Email Templates

If you haven’t seen our eComm email templates, be sure to take a look . They’ve been thoroughly tested and designed to meet CU brand standards.

Data Tags
eComm knows a lot about each constituent. Insert data tags to customize messages so the email appears to have been created just for the recipient. For example, insert a first name tag which is much more engaging than just saying “Dear CU Alum.”

Conditional Tags
Conditional tags allow you to customize one message to different recipients.

Storing Images
Find and store your images the Email Marketing File Library: Email Marketing > File Manager > Campus > Unit’s Name

Do not store images on a desktop or on a shared drive at CU. They will not appear in the sent message.

Resizing Images

  • Resize images in Photoshop
  • Use the save option: Save for web and devices
  • Save as .jpg or .png
  • Do not try to resize images within the Harris editor, as this changes the height and width of images, but does not reduce the file size of the actual image
  • If you must modify an image within Harris, use the corners of the image and never the sides of the image

Image Sizes

Email header

  • Horizontal header (such as the logo and school name across the top of the email) images must be 600px (wide) x 245px (height)

  • The height is flexible, it can be increased to 300px or more depending on the proportions of the image

Images in the message body

  • Image size (image within body copy) should be approximately 150 pixels (px) x 100px or

  • 250px x 250 px

  • Image file size should be less than 250kb

  • Keep the images proportionate, and in line with text

  • Do not use too many images in one email. This makes the file size too large and the email will download slowly or not at all

  • Use “alternate text." This is text that will appear if your constituent does not download images in email or on their phone to let them know something is supposed to be in this location. Keep the description short, ex: “1952 Class Photo”

Your message should be:

  • Relevant to your recipients
  • Short and sweet
  • Compelling visuals are always helpful
  • Include a call to action

All of the following elements are included in our eComm email templates:

  • Unsubscribe link: Link to your University of Colorado campus online communities
  • Open count tag: Contact info in footer, include address, phone, website and email
  • A place for content

Address & Assemble is one of the most important aspects of building out your email because it’s the first thing people see when they receive your message.

Friendly From
A Friendly From definition is another way of saying from whom the email is coming. It should be from someone they recognize. For example, From the Dean of Arts & Sciences will get more opens than From Joe Nobody. If you need your definitions updated or changed, contact your eComm specialist.

A note about Gmail: Make sure your Friendly from is less than 25 characters because Gmail will strip the entire thing and replace it with a period. 

From Email Address
The From email address is displayed next to and should relate to the Friendly From. It looks strange to recipients if the Friendly From reads Chancellor Somebody [joe.nobody@cu.edu]. A better option would be Chancellor Somebody [chancellorsomebody@cu.edu] or even [schoolofX@cu.edu]– even if Joe Nobody is monitoring that inbox. One more thing, the From email address should be an alias email address that your leader is not monitoring (unless they give their permission).

Reply-to Email Address
The Reply-to email address can be the same as the From email address or different. This is a great place to have emails go to joenobody@cu.edu.

Note that out-of-office and other auto-replies are delivered to the Reply-to email address.

This is a great opportunity to include personalized information first name by using a data tag such as first name and last name.


The more you customize your email, the more likely your recipients will open your email.

Note that this is in the email header not in the email’s body content.

BCC should include all internal people that you might want to receive the email when it is delivered. You might want to include your boss, your boss’s boss and your boss’s boss’s boss. A BCC recipient will see the word “SENT” preceding the subject line, therefore serving as a confirmation that the email was sent.

It should be simple, relevant and less than 50 characters. If “CU” isn’t in your Friendly From, be sure to include it in your subject line. Stats show there are improved open rates when the word, "CU" is in the subject line.



Selecting the proper category ensures we are CAN-SPAM compliant and that recipients receive only the emails they want to receive. 

Spam doesn’t always come in a can. Here's a few helpful tips to keep your email from being considered spam

  • Use normal conversational language and always be sure not to use excessive spacing and or capitalization in your subject.
  • Never say “free” or “click here ” or “click here now ” or “act now ” or “limited time ”
  • Do not use “cute” spellings, don’t S.P.A.C.E out your words, don’t put str@nge |etters 0r character$ into your emails.
  • An HTML email is nothing but a bunch of pretty graphics. You need some text in your message, too. Otherwise, the spam filters will have nothing to read and will think your message is junk.
  • Don’t send the HTML email by itself. Always include that plaintext alternative message.
  • If you’re sending HTML emails, use high quality HTML coding. Don’t use tools that generate horrendous HTML (example: MS Word). They often leave signs behind, which are generally found in spam. Unbalanced tags and invalid tags will also flag an email as spam.

Musicians don’t go on stage without doing a sound check and you shouldn’t be sending an email without testing, testing, and testing again.  You would be surprised at how differently your email will look in Gmail as compared to Yahoo and on an iPhone compared to on an Android.

Before sending your email, be sure to test its layout and design in a number of different email clients and web environments. Develop a network of office peers or select constituents to send your test emails so a fresh pair of eyes can always proofread your hard work before it hits the masses. If you work on a deserted island by yourself or have no friends to send to, set up a few mock email accounts and send tests to those accounts.

Testing Environments

Web Clients: Gmail, Hotmail, AOL, Yahoo

Desktop clients: Microsoft Outlook, Outlook Express, Windows (Mac) Apple Mail, Entourage

Web browsers: Internet Explorer, Firefox, Safari, Chrome

Mobile devices: Android, Blackberry, iPhone, Windows Phone

Now that you’re a pro at sending amazing emails, make your next round even better.

Taking the time to review your email delivery statistics is critical. Experiment with open, click, unsubscribe and bounceback rates as well as subject line, personalized data tags in your content, html design and timing of delivery.

One more thing that’s outside of the eComm world; check your website traffic logs after each email campaign. Does traffic pick up?

Use these metrics to inform how to build your next email campaign.