October 21, 2015
Case Study

Email Marketing: Cleansing 50,000 email addresses increases email-to-website traffic by 90%

SUMMARY: Facing major issues with its email campaigns, all of Metropolis International’s brands were affected as its email servers were blacklisted for two months. With no email marketing activity or online revenue coming through the channel, the team knew a major transformation was vital.

See how, through a six-step process, the email team at Metropolis was able to cleanse nearly 50,000 invalid email addresses and improve Sender Score levels 94%.

by Courtney Eckerle, Manager of Editorial Content


Metropolis International is a fast-growing group that was established in 1994 and currently employs around 350 people, with offices in West London, Croydon, Bolton, Frome, Plymouth, Dublin, Chester and New York.

Metropolis specializes in business and consumer media, discount and loyalty programs and business software.

"Metropolis is a kind of federation of businesses. So what we do is we have a list of B2B and consumer media brands as well. Our customers are … mainly [a] B2B audience [who] specialize into … electronics and audiovisual industry, real estate, travel retail, finance and mortgage, medical science and so on," Laz Tyrekidis, Digital Marketing and Audience Director, Metropolis International, said.

Across the 31 brands, a majority of 24 cover B2B with a small percentage reaching out to the B2C audience, he added.


Tyrekidis' journey at Metropolis started in May 2014 when he was enlisted by the company to address the company's struggling email marketing strategy.

All of Metropolis International's brands were affected because its email servers were blacklisted earlier that year, causing no email marketing activity or online revenue to occur in this channel for two months.

"When I joined the team, when I joined Metropolis, the first [thing] that I had to do was to overcome this barrier, make sure that we're going to resolve all of the issues and we continue with a new strategy that is going to guarantee that we're not going to have any problems moving forward," he said.


Tyrekidis set out to ensure email deliverability, optimize the email database and enhance online performance across all 24 B2B brands.

He set up a plan featuring six action points that would help Metropolis achieve a healthy email marketing strategy:
  • Cleanse invalid contacts

  • Re-engage inactive contacts

  • Segment lists

  • Redevelop email templates

  • Optimize for mobile and tablet devices

  • Review email campaign content and scheduling

Step #1. Begin list cleansing

Tyrekidis and his team began by working together with their ESP provider to identify and cleanse the Metropolis database of invalid contacts.

The team managed to clean and remove about 50,000 email addresses from the company's database, according to Tyrekidis.

"Those email addresses were flagged as invalid, and when I say they are invalid, I mean they are emails that there are no replies, bad MX records and obviously the more risky ones — the spam traps," he said.

Tyrekidis was very pleased with this effort, asserting this cleanse reduced the bounce rate of the email campaigns from 2.8% in May 2014 to 1.3% in March 2015.

"This database cleansing process that we started actually helped a lot and improved those sender score levels as well," he said. "So our current sender score levels are up 94%, which is excellent."

Alongside the beginning of the database cleansing process, the team also wanted to ensure the structure of their email servers was set up correctly. This meant setting up different servers and accounts for the brands in order to manage the send volumes of campaigns and mitigate any potential damage.

Step #2. Segment and reactivate subscribers

The second action point involved the segmentation and re-engagement of inactive contacts, Tyrekidis explained.

Originally, he said, Metropolis had many of its emails under one list.

"So what we did is we tried to segment the list and the contacts into our database by offering lots of preferences and options to our users so they can select exactly what type of updates they want to receive," he said.

Instead of having a big pot of email addresses, the team decided to segment the data and segment people based on their interest in specific types of messages or communication.

"We did proceed with the segmentation of email address[es], and at the same time we increased … the volume of the email campaigns we'll be sending trying to reach the same contacts in a more sophisticated way," he said.

According to Tyrekidis, instead of sending one email campaign to 50,000 people, the team decided to segment the database and send five email campaigns to 10,000 people. Each campaign would have a different message based on the list they were opted into.

"We increased the volume of the email campaigns we were sending on a monthly basis by 30%, but it doesn't mean that we changed the frequency or … we started oversending email campaigns to our database," he said.

At this point, Tyrekidis and the email team worked together with the marketing team and the digital marketing team to create a strategy focused on re-engaging with inactive contacts of the database.

"We knew that also we could blacklist it. We knew that there were lots of email addresses that were either bad email addresses or … that have never opened or clicked on any email campaigns in the last six months, since we started doing the re-engagement campaign," he said.

Tyrekidis and the email team defined the inactive contacts by saying they were going to flag inactive contacts who didn't engage — open or click — on email campaigns in the previous six months.

The team began writing email campaigns to engage those people who fell in this six-month gap with questions and information-gathering tactics.

The team ran surveys and a competition, according to Tyrekidis, beginning with a campaign that informed people the email campaigns would be changing.

"We're taking a more professional approach so we would like to hear more from them and give them ... obvious options if they want to change their preferences or unsubscribe from our email campaigns," he said.

By giving subscribers those options, he added, it makes it clear how the company will be handling their data.

"'Your data is safe here' — try to make them feel confident about that. There were lots of different campaigns we've been running based on that," he said.

In this stage, the team was able to increase the active contacts in the database by an additional 10%, Tyrekidis said.

Step #3. Review campaigns for optimization possibilities

In the next stage, the team began reviewing email campaigns, content and time schedules.

"That was something quite important for us," Tyrekidis said, because in previous years, email campaigns had been sent not based on a concrete schedule but based on the availability of the teams.

"We tried to define three different time slots, three different time slots per brand. We reviewed actual email campaigns we had been sending before," he said. "So we viewed stats from January 2014 to December 2014, and this actually included 3,500 email campaigns."

After reviewing those campaigns and send date and times, "we defined three best slots per brand, knowing that on a daily basis we have three best slots that we should use and we are allowed to use," he said.

There are three different types of campaigns Metropolis generally sends, he added:
  • Editorial emails

  • Marketing messages (events, awards, etc.)

  • Industry updates

The team learned the best send time for the different industries and optimized the content that was included in them by these three categories.

Step #4. Make templates mobile responsive

"Obviously we did have a huge bag of email templates that we had been using across all of our brands," Tyrekidis said. "You can imagine 31 brands, lots of different email campaigns, so there were hundreds of different email templates."

This was one of the biggest challenges his team faced, he added. The previous templates were old fashioned and hurting deliverability. They were also not mobile responsive.

"These email templates were not mobile responsive," he said. "After fixing the issues and optimizing our email strategy, that was the next thing I wanted to do — make sure the email campaigns will be visible through mobile devices and tablets."

The team began working to change the email templates, keeping in mind the new designs should be 100% responsive for mobile.

"We changed our email templates across all the brands, making them mobile-responsive, optimizing the HTML code," he said. "By enhancing the code and making them mobile-responsive, we had the fantastic metric here because we managed to improve email opens through mobile and other devices by 380% compared to May 2014."

The new templates now had a clean, linear desktop version:

View the Creative Sample

Click here to see the full version of this creative sample

There was also a mobile version optimized for viewing on that platform, featuring clickable buttons for readers to easily navigate:

View the Creative Sample

Click here to see the full version of this creative sample

Tyrekidis pushed this effort through with proof of industry standards that practically require responsive design in B2B, because "they are at work … [our customers] might be people who are on the move all of the time. So what these people do is they check their email on their mobile device."

"We're seeing that there was a great opportunity here. It was a great opportunity because, at the same time, we had optimized all of the websites of these magazines as well to have a mobile-friendly theme," he said.


"From getting blacklisted, we managed to increase our email opens by 60%. We managed to increase the traffic coming from the email campaigns into the brand website by 90%, and we managed to increase the online revenue by 8% in 10 months, from May 2014 when we started this journey until March 2015," Tyrekidis said.

This is only the end of his first phase for improving the Metropolis email program, he added. The team is currently in phase two.

"So what we are covering in phase two is we do more … optimization and A/B testing. What we are working on at the moment, knowing that we had this big increase on mobile opens as well, is we're working [on] optimizing the subject lines and optimizing the content and templates and the structure of the email campaigns," he said.

For example, the team has begun testing not only email subject lines but also the pre-header snippet seen on mobile devices as well.

"We're working on this kind of optimization, and our plan is to have a stable email marketing strategy, stable online performance and online revenue, organic growth and, on the other side, to do the optimization to increase email opens and email clicks," he concluded.

Creative Samples

  1. Desktop template

  2. Mobile template


Metropolis International

Related Resources

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