How MailChimp Is Benefiting From the Return of Serial

And perhaps no advertiser has reaped the benefits like email-marketing service MailChimp, which became almost as big a hit as Sarah Koenig's weekly dive into the true-crime murder case of Adnan Syed.

So, when Serial returned last week for its second season, listeners expressed their delight about once again hearing the now famous 20-second callout in which a young kid mispronounces the name "MailKimp."

I love that @Mailchimp is still a sponsor!! YAS @serial #serial #serialpodcast #SerialSeason2 #mailkimp

— teresa (@tlamjam) December 10, 2015

Omg I missed #MailKimp girl so much #Serial

— Logan Smith (@LoganJames) December 10, 2015

Big ups to Mail Chimp for sticking to the same "mail keemp?" spot in #Serial season 2. Give the people what they want.

— Lindsay Applebaum (@lindsapple) December 10, 2015

When the Mail Chimp ad starts at the beginning of @serial pic.twitter.com/rvytylwKQ1

— John Not Jon (@pdxbrocialite) December 10, 2015

Because of the podcast's popularity—the first season of Serial has more than 100 million downloads and averages 8 million downloads per episode—Amazon's Audible and Squarespace joined MailChimp as launch sponsors. 

"The substantial lift MailChimp saw in organic conversation over Serial's other two advertisers indicates that they're effectively and efficiently engaging their listeners, as the majority of conversation reflected listener satisfaction with the 'MailKimp' ad's return," said Jason Klein, co-founder and co-CEO of analytics firm ListenFirst Media, which measured online engagement surrounding the three brands.

On Twitter, MailChimp saw an 81 percent spike in mentions from Dec. 9 (the day before the premiere) to Dec. 10. Audible had a 19 percent increase, and mentions for Squarespace actually decreased.

ListenFirst also measured search volume on Wikipedia compared to the first week of last season and found that the email vendor saw a 67 percent increase in searches. (Squarespace and Audible didn't start advertising on Serial until midway through the first season.)

Serial has not yet released data on Season 2 downloads, though the first episode has been the top podcast on iTunes since it launched. The second episode was released Thursday. Season 2 also has increased distribution because of a deal with Pandora, which has 78 million monthly listeners, though the music-streaming service is selling advertising separately.