Litmus and Warmup Inbox are email deliverability tools for marketers and outreach teams who want mail to reach the inbox. Litmus is built to preview how campaigns render across mail clients and to catch an email that breaks after the send. Warmup Inbox is built to grow a mailbox's sender reputation before cold outreach. Enterprise email teams and designers are the usual Litmus buyers, while agencies, sales teams and new senders fit Warmup Inbox.
by Validity
Pricing: No public prices; sold as part of Validity Engage and quoted by the sales team
Litmus is an email testing and deliverability tool for marketing teams that previews campaigns across clients and monitors inbox placement, owned by Validity.
Pricing: Per inbox, per month: Basic $15 (75 warm-ups/day), Pro $49 (250/day), Max $79 (1,000/day). 15+ inboxes need a Custom quote. 7-day trial, no card.
Warmup Inbox builds a mailbox's sender reputation with real traffic across a 30,000+ inbox network, then reports placement and reputation, priced per inbox.
Email Deliverability Tools features side-by-side
Per inbox, per month: Basic $15 (75 warm-ups/day), Pro $49 (250/day), Max $79 (1,000/day). 15+ inboxes need a Custom quote. 7-day trial, no card.
Choose Litmus if you run an enterprise email team that wants every campaign previewed across mail clients and approved before it goes out. Choose Warmup Inbox if you are a new sender or agency that must warm mailboxes before cold outreach. Warmup Inbox is bought on paid plans billed by the month, with higher plans sold by quote.
An email designer or deliverability specialist gets a lot from Litmus before a campaign goes out. It shows how a message renders across mail clients and devices, and it routes drafts through review and approval. Litmus also sends email, Slack or webhook alerts when placement, reputation or a blocklist status changes. Its limit is fit, since it is made for enterprise teams that send at high volume through a large email platform.
A new sender with a cold domain is the buyer Warmup Inbox is made for. Warmup Inbox swaps genuine, human-like messages across a large inbox network, so a mailbox builds reputation automatically. A deliverability testing API also runs placement tests and pulls results for developers. One limit is that its warm-up messages can look computer-generated or flood the connected inbox.
Users of Litmus value its reporting, analytics and engagement tracking, and they call its client previews, test sends and spam checks handy and simple. Billing is their complaint, as charges keep coming after a trial and refunds are refused. Warmup Inbox users like the fast, personal support and easy setup, and some report better inbox placement after warming. The same users complain that Google or Microsoft suspends a mailbox soon after connecting, and that refunds are difficult.
Litmus tells of a digital marketing agency that wanted a smoother email workflow for its clients. The agency reports better deliverability, shorter campaign time and sharper email accuracy. One Warmup Inbox customer, a B2B ecommerce company, wanted to repair its deliverability. The company connected its inboxes and paired warm-up with a spam word checker and a placement tester, and deliverability rose while open rates climbed.
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