MailChimp for WordPress
We actually use MailChimp. It does cause site drag — unless you offload the signup page to their server instead of your own. Read about it here.

On the Internet, there exist widgets – or interface components. They allow connecting your site to specialty services. These are sometimes called third-party integrations or API (such as Facebook, Twitter, YouTube videos, Google Fonts, Google Analytics, CDNs, etc.).

We call them annoying – because they usually slow down page load time. Under ideal conditions, they can be fast. But because you call (HTTP request) to a remote server, that server’s engagement is unpredictable. There can be long, random delays. Then we’re at their mercy. We’ve seen 1- to 2-second delays for third-party add-ons. And in bad cases, more than 8 seconds. Ugh! These delays are essentially “waiting in line” for service. It’s peak traffic dependent.

In an ideal situation, what time delay might we expect for a third-party email service?

We’re all about speed. So we need to set a proper example. Yet, we also desire “free.” And MailChimp’s free email service sounds enticing. Is it fast enough for us? Yes. 36 millisecond load time with the right plugin. There are ways to do this without a plugin – but we found it particularly easy.

With MailChimp, you can send 12,000 emails a month to a list of up to 2,000 subscribers – free!

MailChimp provides an API key for access control using free, signup form plugins.

After setting up a free MailChimp account, adding a form to our site was a piece of cake. We used WP Subscribe, a lightweight opt-in form plugin for WordPress. The widget supports several email providers – currently MailChimp, AWeber and Feedburner. You can then customize the basic signup text used in the opt-in form. Just click the “Labels” option right inside the widget. To customize colors, you need to dig into CSS – and add code to the customizer or a child theme. We did that. An explanation of changing default colors is on the WP Subscribe plugin forum. Here’s a link to a CSS example.

WP Subscribe Features

• Customizable text.
• Add to multiple widget areas.
• Supports MailChimp, AWeber and Feedburner.
• Mobile responsive.
• Free!

Here are two typical experiences from our experiments:

WP Subscribe plugin
MailChimp (without CSS minification)
40,000+ installs, 61k download
Using WP Subscribe plugin with MailChimp adds:
2 requests, 2.6k weight, and 88 milliseconds load time.
No improvement with minification (concatenation). This happens because of the way WP Subscribe plugin is coded.

Yikes Easy Forms for MailChimp plugin
50,000+ installs, 3.7M download
3 HTTP requests, 4.5k page weight, 93 milliseconds load time.
This plugin is coded so minification is a big benefit. Concatenating and minifying with Autoptimize plugin reduced load time to 36 milliseconds for all theme and plugin CSS files. Bonus!

A demonstration of potential speed differences.

iContact (a MailChimp competitor)
5 HTTP requests, 5.5k weight, and 783 milliseconds load time. MailChimp is 10 times faster than iContact.
There is no benefit from concatenation or minification with iContact. The form is created by embedding iContact supplied CSS in a theme text widget.

A note: Each request can load in parallel speeding up load times. It depends upon your server configuration and user’s browser.

16 Alternatives to MailChimp:

Get Response
1,000 list, $15/mo.
https://wordpress.org/plugins/getresponse-integration/
10,000+ installs, 1M download.

SparkPost
Send 100K emails/month for free.
https://wordpress.org/plugins/sparkpost/
8,000+ installs, 35k download.

Active Campaign
1,000 contacts, unlimited sending, $17/mo., 14-day trial.
https://wordpress.org/plugins/activecampaign-subscription-forms/
10,000+ installs, 396k download.

Aweber
30-day free trial, $19/mo. for up to 500 subscribers and unlimited emails.
https://wordpress.org/plugins/aweber-web-form-widget/
10,000+ installs, 35k download.

Emma
10,000 contacts, $89/mo., free trial account
https://wordpress.org/plugins/emma-emarketing-plugin/
1,000+ installs, 73k download

iContact
500 subscribers, $14/mo
https://wordpress.org/plugins/icontact-widget/
2,000+ installs, 166k download

Constant Contact
Free trial for your first 60 days. 500 list size, $20/mo
https://wordpress.org/plugins/constant-contact-forms/
100,000+ installs, 2.2M download

sendinblue
SendInBlue 9,000 free emails per month, unlimited contacts. There are daily sending limits and the SendInBlue logo is visible on all emails.
https://wordpress.org/plugins/mailin/
10,000+ installs, 2.7M download

madmimi
MadMimi – free plan for 100 subscribers.
https://wordpress.org/plugins/mad-mimi-wp/
100+ installs, 741k

activetrail
Target Hero – This free plan includes 1,000 contacts and unlimited emails. Target Hero requires SMS verification to activate an account. If you don’t text, you won’t be able to start an account.
https://wordpress.org/plugins/activetrail-free-email-signup-form/
100+ installs, 111k download

zender.sharptag
Send unlimited number of emails, no credit card needed.

mailerlite
1,000 subscribers, Unlimited emails / month, Free
https://wordpress.org/plugins/official-mailerlite-sign-up-forms/
8,000+ installs, 1.6M download

swipemail.io
Send up to 2,000 emails for free with our 30-day trial—no credit card required.

growmail.co.uk
send 500 Emails / month, free

mailigen.com/special/partnersprogram
forever free Mailigen plan starting with 3000 subscribers.
https://wordpress.org/plugins/mailigen-widget/
80+ installs, 435k download

freshmail
free, 2000 emails to 500 subscribers per month.
https://wordpress.org/plugins/freshmail-integration/
800+ installs, 184k download

benchmarkemail
Upload up to 2,000 subscribers and send up to 14,000 emails per month for free.
https://wordpress.org/plugins/benchmark-email-lite/
2,000+ installs, 89.2k download