This is a topic we’ve covered extensively in the past, including posts on words to avoid and another highlighting six case studies on how to write effective email subject lines.

Many of the same rules apply to mobile, but here are a few tips and examples that will hopefully aid your own efforts…

1. Note the precedence given to the sender’s name

In many mobile inbox providers (e.g. Gmail, Outlook and Apple Mail) the sender’s name is given precedence over the subject line.

This means that it’s very important to select a name that will be familiar to the recipient and doesn’t leave them guessing as to who the message is from.

If you give people any excuse to delete a marketing email then they’ll happily take it.

These are examples taken from my own inbox. In the screenshot on the left all the sender’s names are clear and obvious, however on the right some of messages display email addresses as the sender’s name.


This looks untidy and makes the messages appear a bit spammy when compared to the others.

2. Keep them short

Outlook only allows you to squeeze around 42 characters into a mobile subject line while Gmail gives a far more generous cut off point of roughly 74 characters.

But even though Google allows senders more freedom, it’s advisable to keep subject lines short so that they’re optimised for all inbox providers.

This adheres to accepted best practice, as studies have shown that subject lines are most effective when kept to below 50 characters.

In fact research from Mailer Mailer published back in 2012 showed that four to 15 character subject lines have the highest open rates.

Obviously it’s up to marketers to test their own messages and see what works for their business, and it’s also best to include some variety in email subject lines rather than always opting for the same tactic.

But sticking below about 45 characters is still a decent rule of thumb if you want mobile users to get the message.

In these examples taken from my Outlook app you can see that in general fashion retailers are good at writing short subject lines, although Rue La La should consider being more concise.


3. Keep it simple

Concise writing is a difficult skill, but simple subject lines are often the most effective.

Take these examples from the likes of ASOS, Currys, H&M and other retailers:

  • 25% off your holiday checklist
  • Top 5: New Arrivals
  • Amazing Bank Holiday offers
  • Up to 50% off online
  • Exclusively for you…
  • Brand spanking new stuff!
  • Time to party? We’ve got the look

Each is short and to the point, conveying one idea that gives enough to pique the reader’s interest.

4. Create a sense of urgency

We all know that mobile users have short attention spans, and research has shown that people often use their smartphone simply as a way of filtering email messages before dealing with the important ones on desktop.

So, to give yourself the best chance of actually getting someone to read your email a good tactic is to create a sense of urgency. 

Again, this isn’t something that will work if you use it incessantly, but every now and again it helps to gee your audience into action.

House of Fraser may have overstepped the overstepped the mark slightly in this example with its use of capital letters, but ‘EXCLUSIVELY ONLINE NOW!’ is certainly an attention-grabbing opening.


The Macy’s, ASOS and H&M subject lines are also excellent examples of front-loaded subject lines that create urgency by setting a deadline:

  • Ends Tomorrow
  • 48hrs only
  • Last day