Although emojis in subject lines can increase the open rate by 1.09%, there is little impact on the click-through and click-to-open rates.

Click-through rates see a 003% drop when emojis are used in the subject line, and click-to-open rates see a 0.55% drop. Therefore, although emojis may seem like a nice addition to your email and make them stand out more in a users inbox, they have little to no impact on your conversions.

As an alternative to just using emojis, marketers could consider incorporating clear call to actions and in their subject lines, which could also include an emoji to brighten them up. Knowing when to use emojis and when not to is something you should be aware of, for more serious subjects with a harsher tone of voice, emojis may not be appropriate, however for an email marketing campaign that perhaps has a lighter subject relating to holidays or a seasonal event such as Christmas, emojis can be a great addition and liven up your emails. 

Source: Get Response (