How much email is too much email? That is the question.

Marketers need to strike a fine balance between staying top of mind and relevant to their customers without overwhelming them or coming across as spammy.

The frequency in which companies send email messages varies depending on the industry, business model and time of year, and should also be influenced by targeting and segmentation.

Ultimately each company will have their own formula for email marketing, but there are still some useful case studies available that can act as a starting point for testing new campaigns.

One that recently arrived in my inbox came courtesy of insurance company Aviva, which achieved a 48% increase in the number of car and home insurance quotes requested by prospective customers after adopting a ‘send more email’ approach.

Previously Aviva had only contacted prospects in the month before they were due to renew their policy, but the insurer embarked on a new campaign in 2013 to reach out to prospective customers more often and throughout the year.

After analysing metrics from Aviva’s previous campaigns, email agency Alchemy Worx estimated that Aviva could at least double the proportion of prospects clicking on its emails each year by changing its contact strategy.

Email frequency was increased incrementally after conducting surveys to determine what type of content users wanted in a newsletter, what elements of insurance were most important to them and what their perceptions were of email and frequency.

The programme afforded Aviva the opportunity to promote the benefits of its products in much greater breadth and allowed the company to include useful information on factors to consider when choosing an insurance policy. 

Click here to see a full size version of one of Aviva’s emails

In addition to product-focused messages, the programme included a content-driven newsletter with value-added content such as tips for looking after your car or property.

This new strategy resulted in a quadrupling of both the number of unique clicks (304%) and total clicks (292%) from the emails sent.

But while an increase in email frequency proved to be successful for Aviva, these two studies show that the opposite can also be true…

Frequency is more important than relevance

According to a survey by BlueHornet more than a third (35.4%) of consumers site frequency as the main reason they unsubscribe from email newsletter.

The study also found that almost half (47.1%) of respondents would always or sometimes ‘opt-down’ and receive fewer emails rather than hit the unsubscribe button, if that option were on offer.

The survey was administered to a national panel of 1,002 consumers across the US between the ages 25 and 40.

Frequency goes up, engagement goes down

A study from MailChimp has established that frequency and engagement are negatively correlated, meaning that as marketers send email more frequently their customers tend to engage less with each campaign.

The methodology was quite complex, but essentially it looked at the click rate for marketers that had substantially varied their send frequency over time.

The results showed that the campaign click rate decreased as email frequency increased.

Here are the results from two companies, which shows the impact that frequency has on engagement:

Example 1 

Example 2

So which approach is best?

In reality there isn’t a concrete answer to this question. Email frequency is influenced by a range of factors, as mentioned at the top of this post.

The best advice is to test your email marketing and segment your audience so that messages are tailored to customer behaviour.

As Tim Roe explained in his post on why ‘more email means more money’, marketers stand to benefit from sending additional, targeted campaigns to their most responsive customers. 

Frequency isn’t just about sending more or less emails to everyone; it’s about sending the right amount of emails, to the right people.

Finally, marketers should also try altering their email frequency depending on the time of year. For example, guest bloggers Andrew King and Parry Malm have both discussed the merits of increasing email messaging in the lead up to Christmas.