What an email validator can and cannot tell you before sending

An email address that looks valid can fail to send when attempted to be sent to. Additionally, a domain can accept mail but not confirm that a particular email address actually exists for that domain. Thus, it is crucial to perform an email-list check that relates the results to the reasons for the results as well as to the degree of uncertainty associated with the results. An email-validator’s output should not consist of a simple checkmark next to each address in the list to indicate whether or not that address is valid.

Keep every row in the review

Start with the actual list that you will test: a copy and paste into the Email Validator app of the addresses you have in a list, or a copy and paste of the whole rows of a CSV file that you have in a spreadsheet. Include all of the fields of the original list, so that your team can understand the full information in each row. If there are two rows with identical addresses, then it would be helpful to see both of those.

An Email Validator application, such as the Email Validator app from Recurse, is generally used to generate a report, typically in the form of a CSV/JSON file that specifies the status of each email address listed in the input. This report includes the reasons for the status (e.g. the specific error) for each email address. The status of the Email Validator app checks for an email address can indicate whether an address appears to be ‘malformed’ or reports ‘domain problems’ but it cannot establish whether the owner of a mailbox actually is a person and therefore whether they will receive a message in their ‘inbox’ and whether you have permission to send them email.

Read the reason before acting

When checking for malformed addresses, domain issues with an address’ sending status, an uncertain result from an email-list check should be left uncertain by your Email Validator app. Don’t translate ‘we could not verify this mailbox’ to ‘this address is valid’. If the sender ip is invalid for an address, that needs to be fixed at the sender’s source – it’s not a problem for the Email Validator app to report.

Here’s a simple review table. You can use it to determine whether to correct an address from a trusted source, to ask someone to verify an address, or to leave an uncertain address in the list for now. You can also print the reason that the email address validator gave for an address that was excluded from a campaign by that user, to discuss with them later.

Validate the process, not just the syntax

These steps comprise a portion of list hygiene. Delivery, consent, and engagement are separate issues that require separate checks.

A useful report separates incorrect input from uncertain results and preserves the available evidence. Start with Recurse’s email verification task to ask your agent to check a small list and explain valid, invalid, catch-all or unknown results.