MailChimp has two different settings for sending welcome emails to your users depending on whether you've enabled or disabled double opt-in.
When Double Optin is Enabled
If you've turned on Double Optin, MailChimp allows you to set a "Final Welcome Email". As soon as somebody subscribes to your opt-in form, MailChimp will first send them a confirmation email asking them to verify their email address. Once they've verified their email address, MailChimp can send a "Final Welcome Email" if you've enabled it. To do that, please visit: http://kb.mailchimp.com/lists/signup-forms/enable-final-welcome-email
When Double Optin is Disabled
If you've disabled Double Optin, MailChimp does not send the "Final Welcome Email" even if its enabled. In this case, you'll have to create an "Automation Workflow" to send Welcome Email to your subscribers. To accomplish this, follow the easy steps mentioned below.
Step 1: Login to your Mailchimp account.
Step 2: Click on the Automation tab on the top. You should see the following screen. Click on the Create Automation Workflow button on the top right corner of the screen.
Step 3: Choose the list from the Select a list drop-down within which the subscribers would be receiving the welcome email. For example, we selected Personal Users.
Step 4: On the right side, you'll see a list of workflows. Choose "Welcome Message".
Step 5: Fill in the details about your workflow in the next step, and hit "Next" at the bottom right of the screen.
Step 6: Make sure to check the Trigger workflow when subscribers are imported option. Click "Next" at the bottom right to proceed.
Step 7: Add emails to your workflow. Click on the Add Email button.
Step 8: As soon as your first Automation Email is added, you'll see an option to Change delay to adjust when to trigger the email.
Step 9: Change the wait time to immediately, so that welcome emails are sent as soon as someone subscribes. Check the Apply to all option, and then click on the Save button to proceed.
Step 10: Click on the Design Email button, it is present next to the Automation Email. This will lead you to the Email Template and Design flow. Enter details, and click on "Next" to proceed.
Step 11: Choose a template.
Step 12: Edit the default placeholder text.
Step 13: Make sure you select the option of As soon as possible under "What time should emails be sent?"
Step 14: Click on "Save and Continue" at the bottom right to return to the automation workflow.
Step 15: You'll see a final checklist of all the items. Everything needs to be marked in green for you to start the workflow.
Step 16: Click on Start Workflow at the bottom right of the screen. Click on the Start Workflow button again to confirm.
Congratulations! You have now setup an automation workflow that will send Welcome Emails to your subscribers as soon as they subscribe from MailMunch opt-in forms.