Using symbols, or emoji in subject lines isn't a new idea. However, now that many of us have emoji-friendly mobile devices and regularly read our email on them, it's become an increasingly popular tactic for attracting attention in crowded inboxes. To see how practical this technique is, we tested out a variety of symbols to see how reliably they display across a range of email popular clients.
The Verdict
Use with caution!Use with caution! Symbols in subject lines are not supported in Outlook 2003 and Lotus Notes. Not all symbols are universally supported either, so make testing an important step in your decision.
Copy, paste
The first point of confusion that folks have when it comes to including symbols in subject lines is how to get them there. We usually use symbol entities in HTML email content, however as subject lines aren't HTML code, what you need to do is copy the symbol from a website/document like Facebook Symbols, then paste it into the subject line field of your campaign.
Symbol support in popular email clients
This copy-paste technique works surprisingly well. We tested a variety of symbols in the most popular email clients and found they were generally well supported:
| Email client | Symbols display in subject line? |
| Outlook 2007/10/13 | Yes |
| Outlook 2003 | No |
| Windows Live Hotmail | Info |
| iPhone / iPad (iOS) | Info |
| Apple Mail | Yes |
| Yahoo! Mail | Yes |
| Gmail | Yes |
| Windows Mail | Yes |
| Android Mail | Yes |
With the exception of Outlook 2003, there was near-universal support. Hotmail and iOS devices included an additional twist - instead of displaying the basic characters, some symbols like ❤ are replaced by 'emoji', or a small graphic instead. Here's a selection in Hotmail:
Keep in mind that if a character isn't supported in the email client, the recipient will see a ☐ character instead.
Finally, we haven't yet managed to trigger spam filters by including symbols in subject lines (and we used a lot of symbols in our tests). However, we'd be keen to hear if you've experienced otherwise.
Our recommendation
Of course, adding symbols to subject lines isn't for everyone. For starters, they don't display in Outlook 2003 and they're perhaps not 'professional' like regular text. However, if you're sending a fun newsletter and want to bring a new weapon into the fight for attention in the inbox, then it's a neat technique to try. Our friends at Litmus anecdotally noted open rate increases of 10-15% as a result of adding symbols to subject lines, so we'd be curious to hear if folks like you have receive comparable results.