Email on Acid vs Validity Engage (2026): which should you pick?

Pick Email on Acid if

• Fits if you check each campaign across many email clients
• Works for agencies that need unlimited users on one account

Look elsewhere if

• Pricey if you add it up, at $99 a month for 1,000 previews
• Skip it if you want accessibility or spam checks on the cheap plan, as they start at Premium, $199
• Watch out: the pricing page says customers move to Mailgun Inspect from June 2026 and old tests are not carried over
• Watch out: it does not send email, so you need a separate sending service
• Watch out: the trial length is not stated

Pick Validity Engage if

• Fits if you send large volumes and need to see inbox placement
• Works for brands with a team watching sender reputation

Look elsewhere if

• Not for you if you want to buy online, as pricing is built to fit through sales
• Skip it if you want a free plan or trial, as none was found
• Watch out: the directory name is Validity Everest, but the vendor's pages call it Validity Engage
• Pricey if you are a small sender, as it is aimed at enterprise sending programs and priced through sales

Email on Acid

• The pricing page says current customers will move to Mailgun Inspect from June 2026, and that old previews and tests are not carried over.
• Annual-plan customers migrate at the end of their current term.
• Basic has no accessibility, spam or link checks; those start at Premium.
• It does not send email; the FAQ says you need a separate sending service.

Validity Engage

• Pricing is built to fit through sales; no plan prices were found on the pages read.
• The directory name is Validity Everest, but the vendor's pages now call the platform Validity Engage.
• Aimed at enterprise programs; a demo is the listed way to get started.
• No self-serve sign-up or free plan was found on the pages read.

Email on Acid

Client and device previews

Each screenshot of a client or device counts as one preview, so a test across 50 clients uses 50 previews.

Accessibility checks

Premium tests are based on the W3C Web Content Accessibility Guidelines, which the vendor ties to the European Accessibility Act.

Link and image validation

Premium checks links and images in a message. The FAQ says these checks, unlike previews, are unlimited.

Spam content analysis

Premium includes content spam checks and HTML code analysis, judged on the message itself and not on your sending reputation.

API access and unlimited users

Every plan includes API access, and none of the plans limit how many people on a team can use the account.

Validity Engage

Inbox placement testing

Shows where a campaign lands across major mailbox providers, using the Validity Intelligence Network, with results split by IP and domain.

Sender reputation monitoring

Tracks Sender Score across IPs and domains so a drop can be seen before it turns into a placement problem.

Authentication monitoring

Checks SPF, DKIM and DMARC configuration and alignment across sending domains and flags when something breaks.

Blocklist monitoring

Alerts when an IP or domain is listed on a blocklist and gives guidance on the trigger and on getting removed.

Pre-send deliverability check

Runs before a campaign goes out and surfaces spam trap, reputation and authentication risks.

Provider-specific signals

Breaks placement and throttling signals out by mailbox provider such as Gmail, Yahoo and Office 365.

Email on Acid

• Basic$99

  per month for 1,000 previews

  Unlimited users, 100+ preview clients and devices, API access; extra previews cost $0.15 each.

• Premium$199

  per month for 2,000 previews

  Adds accessibility tests, HTML code analysis, link and image validation and spam content checks.

• ContractCustom

  Custom preview allotment with the Premium feature set and phone and chat support; sold through sales.

Validity Engage

Pricing could not be confirmed. See validity.com.