Use a contact form plugin that supports multiple notification emails. Configure one notification to go to the site owner (the standard case) and a second one to go to the submitter, populated with your acknowledgement text. That second notification is the autoresponder. Every mainstream form plugin either supports this natively or has a free add-on that adds it.
An autoresponder is not a marketing email tool. It is a one-shot acknowledgement message sent to the person who just submitted a form, confirming their submission arrived and telling them what happens next. For marketing sequences (welcome series, drip campaigns, RSS-to-email), a dedicated email marketing service is the right tool, not a WordPress form plugin.
The per-plugin path
Contact Form 7. CF7’s core supports a “Mail (2)” tab on every form. Check the “Use Mail (2)” box, fill in the recipient with the submitter’s tag (typically [your-email]), set the From address to your domain, and write your acknowledgement copy in the message body. That is the autoresponder. No add-on needed. Third-party add-ons like Contact Form 7 Multi-Step exist for more complex flows but the core Mail (2) feature covers the standard case.
WPForms. Every form has a Notifications section under Settings. Add a second notification, set its “Send To Email Address” to the smart-tag reference for the email field ({field_id="1"} or similar), write the message. Available on all tiers including Lite.
Fluent Forms. Similar to WPForms: add a second Email Notification under the form’s Confirmation & Notifications settings, target the submitter’s field, write the copy. Free tier supports this.
Gravity Forms. The “Notifications” tab per form supports arbitrary numbers of notifications. Add one targeting the submitter’s email field.
Formidable Forms. Its Actions section has Email as one of many action types. Add an Email action, set the “To” to the submitter’s field. The free tier supports one email action; the Business tier supports multiple.
The pattern is the same across all of them
Every autoresponder implementation shares four fields:
- To: the submitter’s email address, referenced via the plugin’s smart-tag or shortcode syntax for the form’s email field.
- From: a fixed address on your domain (
[email protected]or[email protected]), not the submitter’s address. - Subject: typically “Thanks for your message” or a variant referencing the form.
- Body: your acknowledgement copy. Confirmation that the message arrived, an ETA for a personal reply, and any relevant next steps or links.
The From-address field is the one that catches people out. If you put the submitter’s own email address in the From field, the autoresponder will fail DKIM alignment against your domain, and Gmail or Microsoft 365 will reject or spam-folder it. See How do I change the “from” address of emails sent from WordPress? for why this matters and how to set it correctly.
The mail side still has to work
An autoresponder is just another email sent through wp_mail(). If your site’s mail is silently failing, the autoresponder fails silently along with everything else. Two prerequisites:
- A mailer plugin routing
wp_mail()through an authenticated transactional provider. See Can I use a third-party email service with WordPress? and WordPress email setup: the complete guide. - SPF and DKIM published on your domain so the autoresponder authenticates. See DNS for WordPress email.
Without either, the submitter is unlikely to receive the acknowledgement. Test the whole path before assuming it works: submit the form from an external address (Gmail, Outlook.com, whatever) and verify the autoresponder arrives.
What an autoresponder is not
Two adjacent things people sometimes reach for the term “autoresponder” for:
- A drip campaign or welcome series. Multiple pre-written emails sent on a schedule after a trigger event. Different tool: a dedicated email service (Mailchimp, MailerLite, ConvertKit, Brevo). A WordPress form plugin can trigger the sequence by adding the submitter to the service’s list, but the sequence itself lives in that service.
- An out-of-office reply on a personal mailbox. A vacation responder attached to your own inbox. Different tool: your email client or Google Workspace / Microsoft 365 settings.
If what you actually need is a sequence rather than a single acknowledgement, integrate the form with an email service instead. WPForms, Fluent Forms, and Gravity Forms all have first-party integrations with Mailchimp, ActiveCampaign, ConvertKit, HubSpot, and the other major services. See Can messages from my contact form go directly into my CRM? for the analogous CRM integration path.