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Verifalia API - PHP SDK and helper library

This SDK library integrates with Verifalia and allows to verify email addresses in PHP v7.0 and higher.

Verifalia is an online service that provides email verification and mailing list cleaning; it helps businesses reduce their bounce rate, protect their sender reputation, and ensure their email campaigns reach the intended recipients. Verifalia can verify email addresses in real-time and in bulk, using its API or client area; it also offers various features and settings to customize the verification process according to the user’s needs.

Verifalia's email verification process consists of several steps, each taking fractions of a second: it checks the formatting and syntax (RFC 1123, RFC 2821, RFC 2822, RFC 3490, RFC 3696, RFC 4291, RFC 5321, RFC 5322, and RFC 5336) of each email address, the domain and DNS records, the mail exchangers, and the mailbox existence, with support for internationalized domains and mailboxes. It also detects risky email types, such as catch-all, disposable, or spam traps / honeypots.

Verifalia provides detailed and accurate reports for each email verification: it categorizes each email address as Deliverable, Undeliverable, Risky, or Unknown, and assigns one of its exclusive set of over 40 status codes. It also explains the undeliverability reason and provides comprehensive verification details. The service allows the user to choose the desired quality level, the waiting timeout, the deduplication preferences, the data retention settings, and the callback preferences for each verification.

Of course, Verifalia never sends emails to the contacts or shares the user's data with anyone.

To learn more about Verifalia please see https://verifalia.com

Table of contents

• Getting started
  • Naming conventions
  • Authentication
  • Authenticating via Basic Auth
  • Authenticating via bearer token
  • Authenticating via X.509 client certificate (TLS mutual authentication)
• Validating email addresses
  • How to validate / verify an email address
  • How to validate / verify a list of email addresses
  • Processing options
  • Quality level
  • Deduplication mode
  • Data retention
  • Wait options
  • Avoid waiting
  • Progress tracking
  • Completion callbacks
  • Retrieving jobs
  • Don't forget to clean up, when you are done
• Managing credits
  • Getting the credits balance
• Changelog / What's new
  • v3.0

Getting started

The most efficient way to add the Verifalia email verification library into your PHP project is by using composer, which will automatically download and install the required files from Packagist. With composer installed, run the following command from your project's root directory:

For Windows users, the alternative command to run is:

Naming conventions

This package follows the PSR-4 convention names for its classes, meaning you can even load them easily with your own autoloader.

Authentication

First things first: authentication to the Verifalia API is performed by way of either the credentials of your root Verifalia account or of one of your users (previously known as sub-accounts): if you don't have a Verifalia account, just register for a free one. For security reasons, it is always advisable to create and use a dedicated user for accessing the API, as doing so will allow to assign only the specific needed permissions to it.

Learn more about authenticating to the Verifalia API at https://verifalia.com/developers#authentication

Authenticating via Basic Auth

The most straightforward method for authenticating against the Verifalia API involves using a username and password pair. These credentials can be applied during the creation of a new instance of the VerifaliaRestClient class, serving as the initial step for all interactions with the Verifalia API: the provided username and password will be automatically transmitted to the API using the HTTP Basic Auth method.

Authenticating via bearer token

Bearer authentication offers higher security over HTTP Basic Auth, as the latter requires sending the actual credentials on each API call, while the former only requires it on a first, dedicated authentication request. On the other side, the first authentication request needed by Bearer authentication takes a non-negligible time.

⚠️ If you need to perform only a single request, using HTTP Basic Auth (see above) provides the same degree of security and is also faster.

Authenticating via X.509 client certificate (TLS mutual authentication)

In addition to the aforementioned authentication methods, this SDK also supports using a cryptographic X.509 client certificate to authenticate against the Verifalia API, through the TLS protocol. This method, also called mutual TLS authentication (mTLS) or two-way authentication, offers the highest degree of security, as only a cryptographically-derived key (and not the actual credentials) is sent over the wire on each request. What is X.509 TLS client-certificate authentication?

Validating email addresses

Every operation related to verifying / validating email addresses is performed through the emailValidations field exposed by the instance of the VerifaliaRestClient class you created above. The property exposes some useful functions: in the next few paragraphs we are looking at the most used ones, so it is strongly advisable to explore the library and look at the embedded help for other opportunities.

The library automatically waits for the completion of email verification jobs: if needed, it is possible to adjust the wait options and have more control over the entire underlying polling process. Please refer to the Wait options section below for additional details.

How to validate / verify an email address

To validate an email address from a PHP application you can invoke the submit() method: it accepts one or more email addresses and any eventual verification options you wish to pass to Verifalia, including the expected results quality, deduplication preferences, processing priority.

Note In the event you need to verify a list of email addresses, it is advisable to submit them all at once through the submit() method (see the next sections), instead of iterating over the source set and submitting the addresses one by one. Not only the all-at-once method would be faster, it would also allow to detect and mark duplicated items - a feature which is unavailable while verifying the email addresses one by one.

In the following example, we verify an email address with this library, using the default options:

Once submit() completes successfully, the resulting verification job is guaranteed to be completed and its results' data (e.g. its entries field) to be available for use.

As you may expect, each entry may include various additional details about the verified email address:

Here is another example, showing some of the additional result details provided by Verifalia:

How to validate / verify a list of email addresses

To verify a list of email addresses you can still call the submit() function, which also accepts an array of strings with the email addresses to verify:

Processing options

While submitting one or more email addresses for verification, it is possible to specify several options which affect the behavior of the Verifalia processing engine as well as the verification flow from the API consumer standpoint.

Quality level

Verifalia offers three distinct quality levels - namely, Standard, High and Extreme - which rule out how the email verification engine should deal with temporary undeliverability issues, with slower mail exchangers and other potentially transient problems which can affect the quality of the verification results. The ValidationRequest class accepts a quality field which allows to specify the desired quality level; here is an example showing how to verify an email address using the High quality level:

Deduplication mode

The submit() method can also accept and verify multiple email addresses in bulk, and allows to specify how to deal with duplicated entries pertaining to the same input set; Verifalia supports a Safe deduplication mode, which strongly adheres to the old IETF standards, and a Relaxed mode which is more in line with what can be found in the majority of today's mail exchangers configurations.

In the next example, we show how to import and verify a list of email addresses and mark duplicated entries using the Relaxed deduplication mode:

Data retention

Verifalia automatically deletes completed email verification jobs according to the data retention policy defined at the account level, which can be eventually overridden at the user level: one can use the Verifalia clients area to configure these settings.

It is also possible to specify a per-job data retention policy which govern the time to live of a submitted email verification job; to do that, set the retention field of the ValidationRequest instance accordingly.

Here is how, for instance, one can set a data retention policy of 10 minutes while verifying an email address:

Wait options

By default, the submit() method submits an email verification job to Verifalia and waits for its completion; the entire process may require some time to complete depending on the plan of the Verifalia account, the number of email addresses the submission contains, the specified quality level and other network factors including the latency of the mail exchangers under test.

In waiting for the completion of a given email verification job, the library automatically polls the underlying Verifalia API until the results are ready; by default, it tries to take advantage of the long polling mode introduced with the Verifalia API v2.4, which allows to minimize the number of requests and get the verification results faster.

Avoid waiting

In certain scenarios (in a microservice architecture, for example), however, it may be preferable to avoid waiting for a job completion and ask the Verifalia API, instead, to just queue it: in that case, the library would just return the job overview (and not its verification results) and it will be necessary to retrieve the verification results using the get() method.

To do that, it is possible to specify WaitOptions::$noWait as the value for the waitOptions parameter of the submit() method, as shown in the next example:

Progress tracking

For jobs with a large number of email addresses, it could be useful to track progress as they are processed by the Verifalia email verification engine; to do that, it is possible to create an instance of the WaitOptions class and provide a callable which eventually receives progress notifications through the progress field.

Here is how to define a progress notification handler which displays the progress percentage of a submitted job to the console window:

Completion callbacks

Along with each email validation job, it is possible to specify a URL which Verifalia will invoke (POST) once the job completes: this URL must use the HTTPS or HTTP scheme and be publicly accessible over the Internet. To learn more about completion callbacks, please see https://verifalia.com/developers#email-validations-completion-callback

To specify a completion callback URL, pass a ValidationRequest instance to the submit() method and set its completionCallback field accordingly, as shown in the example below:

Note that completion callbacks are invoked asynchronously, and it could take up to several seconds for your callback URL to get invoked.

Retrieving jobs

It is possible to retrieve a job through the get() method, which returns a Validation instance for the desired email verification job. While doing that, the library automatically waits for the completion of the job, and it is possible to adjust this behavior by passing to the aforementioned methods a waitOptions parameter, in the exactly same fashion as described for the submit() method; please see the Wait options section for additional details.

Here is an example showing how to retrieve a job, given its identifier:

Don't forget to clean up, when you are done

Verifalia automatically deletes completed jobs after a configurable data-retention policy (see the related section) but it is strongly advisable that you delete your completed jobs as soon as possible, for privacy and security reasons. To do that, you can invoke the delete() method passing the job Id you wish to get rid of:

Once deleted, a job is gone and there is no way to retrieve its email validation results.

Managing credits

To manage the Verifalia credits for your account you can use the credits property exposed by the VerifaliaRestClient instance created above.

Getting the credits balance

One of the most common tasks you may need to perform on your account is retrieving the available number of free daily credits and credit packs. To do that, you can use the getBalance() method, which returns a Balance object, as shown in the next example:

To add credit packs to your Verifalia account visit https://verifalia.com/client-area#/credits/add.

Changelog / What's new

This section lists the changelog for the current major version of the library: for older versions, please see the project releases.

v3.0

Released on February 1^st, 2024

• Added support for Verifalia API v2.5
• Added support for classification override rules
• Added support for AI-powered suggestions
• Added support for client-certificate authentication
• Added support for bearer authentication
• Added support for completion callbacks
• Added support for submission and polling wait time
• Added PHPDoc annotations
• Improved sleeping time coercion while waiting for job completion
• Breaking change: minimum PHP version requirement increased to PHP 7.0
• Breaking change: the submit() method now, by default, waits for the email verification job to complete
• Breaking change: renamed IAuthenticator interface to AuthenticationProvider