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SafeToSend Results Guide – AtData’s Email Verification

Help Center   ❯  AtData Services   ❯  Email Verification

An explanation of AtData’s SafeToSend email verification and hygiene results and how to use them.

SafeToSend is the industry’s leading Email Verification and Hygiene solution, trusted by twenty-five percent of the Fortune 500. With unparalleled speed and accuracy, SafeToSend protects you from spam traps, bounces, and high risk emails that can threaten your inbox delivery.

SafeToSend can check emails in real-time via our API or process lists of emails. The SafeToSend batch verification process will add up to six fields to your email list: Verification Status, Verification Code, Domain Type, Role Account, Duplicate and Valid Email. If you uploaded a list from your computer, the original fields will be preserved and our results will be appended to the end of each record. If you export your results to your email service provider (“ESP”), these field names will be prefixed with “TD “, e.g. “TD Verification Status”. The Verification fields are described below and together they provide the data you need to assess and clean your list.

Verification Status
This field describes the overall verification result with the following values:

To get the best delivery results and avoid any emails that may bounce or cause delivery issues, only send messages to emails with a status of “safetosend” or “corrected”, which are backed by AtData’s 100% deliverable guarantee. Emails with a “valid” or “catchall” status have passed all syntax and trap checks and can be mailed with little risk, but we could not verify the mailbox and they may bounce. Note that emails you have defined as an exception and should always be allowed will be given a status of “valid” with verification code 55.

For “unknown” status emails, we had no information at the time of processing, but, if they are a small enough percentage of the results, mailing them is unlikely to impact your sender reputation.

Verification Code
AtData’s Verification Codes provide the specific reason why we applied the corresponding Verification Status. Most users will just check the Verification Status, but the Verification Code provides more granular detail.

Get our list of 33 unique verification codes, and below is additional information on how to interpret them.




unknown 5 Timeout. Did not get a response in time.
valid 10 Syntax OK.
valid 20 Syntax OK and the domain is valid.
catchall 45 Domain is a catch all and does not support validation.
safetosend 50 Valid and guaranteed SafeToSend email address.
valid 55 Address is allowed by client-configured exception.
invalid 100 General syntax error.
invalid 110 Invalid character in address.
invalid 115 Invalid domain syntax.
invalid 120 Invalid username syntax.
invalid 125 Invalid username syntax for that domain.
invalid 130 Address is too long.
invalid 140 Address doesn’t have a username.
invalid 145 Address doesn’t have a domain.
invalid 150 Address doesn’t have an @ sign.
invalid 155 Address has more than one @ sign.
invalid 200 Invalid top-level domain (TLD) in address.
invalid 210 Address contains an extra space or character.
invalid 215 Unquoted spaces not allowed in email addresses.
invalid 255 Address is not allowed by client-configured suppression.
invalid 310 Domain doesn’t exist.
invalid 325 Domain can’t receive email.
invalid 400 Mailbox doesn’t exist.
invalid 410 The mailbox is full and can’t receive email.
invalid 420 Mail isn’t accepted for this domain.
invalid 500 Emails with that username aren’t accepted.
invalid 505 Emails with that domain aren’t accepted.
invalid 510 That address isn’t accepted.
invalid 520 Address matched to known bouncers (optional feature).
trap 525 Address is a spamtrap, a known complainer or is suppressed.
trap 530 Address has opted out from commercial email.
unknown 999 System error.

See below for more information on how to interpret specific types of invalid responses:

Invalid – Codes 400 to 420 – Mailbox errors

Within the mailbox errors, there are three possible reasons. Invalid – 400, the mailbox doesn’t exist, is the most common invalid result. Invalid – 410, representing a full mailbox, can be considered a temporary or “soft” bounce, and these addresses may be able to receive messages at a later date.

Codes 55 and 255 — User defined exceptions and suppressions

Within the InstantData interface, you can define usernames, domains and email addresses that should always be allowed or always suppressed by the SafeToSend process. Status “valid” and code 55 indicates we allowed the email due to an exception you defined, and status “invalid” and code 255 indicates we rejected the address due to one of your suppressions.

Invalid – 500 to 520 – Email not accepted

Emails that fall under these codes have usernames, domains or emails that are best to avoid. These include mailboxes such as “abuse@” or domains such as “” which belong to blacklists.

Trap- 525 – Address is a spam trap, a known complainer or is suppressed

This result represents emails that are confirmed spam traps, suspected spam traps, disposable emails, or otherwise considered high risk. This is toxic data, and, typically, these records should be quarantined or discarded. However, some users might want to compare response data by record before eliminating the email address entirely.

You can also provide us your own custom suppression list to be used in marking emails with this code.

Trap – 530 – Address has opted out from commercial email

This represents records that match to a database of over 15 million email addresses that have opted out of receiving third-party email, including the Direct Marketing Association’s Email Preference Service. These records have typically responded to a permission request email in support of email append or to email list rental, and then asked to be excluded from future mailings in that category. You are under no legal obligation to remove them, but may consider doing so to minimize risk and complaint rates.

Domain Type
This field should be used as a reference point. The domain of each email is categorized, by top-level domain or AtData’s analysis, to provide you with insights into where your subscribers reside digitally.

Role Account
These addresses are group mailboxes. For example, “info@” or “sales@”. You might decide that a transactional message to a role-based mailbox is okay, but a marketing message could lead to complaints. Include or remove these records as you see fit.

Duplicate Flag
The value “true” is applied to each additional instance of an email address after the first. The first instance will be blank. For example, if [email protected] appears 3 times on your file, the duplicate flag will only appear next to the second and third listings of this email address.

Valid Email
This field includes only the emails that are guaranteed to be deliverable with verification statuses “safetosend” or “corrected.” This field only appears in files that are downloaded to your computer.