SparkPost Recipient Validation is now available both for existing SparkPost customers and for new, non-sending customers. It uses powerful data-driven analysis on billions of bounce, delivery, and engagement events daily to train our algorithm, bringing you one of the most powerful data-driven email validation tools on the market, so you can send emails smarter.

Dit artikel explains how you can get the most out of the data you’ll receive back on each validated recipient – you’ll see we classify addresses to be “valid”, “risky”, “neutral”, “undeliverable”, and “typo”. We give you a “reason” code and also a “did_you_mean” for known address typos.

API verzoeken

In the SparkPost web app, you can drag & drop an entire list for validation. You can also use de API to validate single addresses, so you can build validation right into your address entry workflow.

A while back we came up with a Python command-line tool using this API. We talked over what we should do for andere languages – and here we are! Let’s get started.

This Github repository map has working Recipient Validation API call examples in around a dozen different languages. We try to cover the meest populaire toepasselijke talen.

De gemeenschappelijke werkwijze bij al deze voorbeelden is:

• Pick up your key from environment variable SPARKPOST_API_KEY

• Make an API call to /api/v1/recipient-validation/single/to validate a recipient

• Een antwoordstring terugontvangen, die JSON-geformatteerde gegevens bevat met het resultaat

• Het resultaat afdrukken

SparkPost has bibliotheken for some, but not all of the languages covered here. We chose to write these examples “native” instead, so we could a) cover more languages, b) show how simple the underlying code can be, and c) enable you to see clearly the similarities and differences between languages.

Bash / Krul

Dit wint de prijs voor de kortste code - het gebruikt gewoon de commandoregeltool "curl" om het verzoek in te dienen en het antwoord rechtstreeks naar de terminal af te drukken. U ziet dat de uitvoer een string is, die JSON bevat; we parsen de individuele resultaatattributen niet.

PHP

Trusty PHP has a few different manieren to make HTTPS API calls. Here we chose to use curl_setopt and curl_exec. (https://www.php.net/manual/en/function.curl-exec.php)

If you prefer HTTP_Request2 or pecl_http, then Postman has a built-in code generator that you can use to create similar examples – just set up a working GET request and use the “Code” button.

Python

This uses the popular requests module, which is high-level and therefore easy to use. This example checks the returned status code, converts the results JSON back into a Python dictionary object, and prints the resulting object rather than just a string.

If you prefer the built-in http.client library, Postman can generate code for that too; it’s not much longer.

Node.js

There are veel verschillende node.js HTTP(S) libraries. I started with the older request package (using a callback function) but it’s deprecated and no longer actively maintained.  I chose the newer axios package (using belooft). 

Postman can also give you a Javascript native example and Unirest, in case you prefer those.

Omdat deze code toegang moet hebben tot uw API-sleutel, raden wij ten zeerste aan onze API aan te roepen vanaf uw server-kant, nooit vanaf de client (browser / mobiel apparaat).

Go

Go strives toward a philosophy of “one good way” to do something; in this case, using the built-in “batteries included” libraries net/http, encoding/json and others.

De length is due mostly naar de explicit error checking clauses if err != nil {} everywhere (geen uitzonderingen LOL).

We declareren ook de structuur van het resultatenobject met veldtags, zodat we de teruggezonden JSON-string kunnen "ontmarsen". We overlappen de tags "resultaten" en "fouten" om beide soorten terugkeer mogelijk te maken.

Ik hou van de snelheid, typeveiligheid en duidelijkheid van Go, ook al is de code langer dan onze vorige voorbeelden.

C#

I’m less familiar with C# – to me, it looks quite Java-like, rather than C-like. I was able to put this together following examples shown in the request library System.Net.Http.

Postman can auto-generate example code using RestSharp, if you prefer that.

Ruby

This was my first attempt at Ruby code; I used the Net::http library, and followed dit voorbeeld (which turns out to be very close naar de code that Postman auto-generates).

I ran into one language / library oddity that’s worth explaining. Just setting up using a URI that begins “https://” is not enough, you have to specifically set http.use_ssl = true. 

Zonder dit, zal je code proberen een verzoek in te dienen op poort 443 - maar zonder gebruik te maken van SSL/TLS (dus gewoon), en SparkPost zal terecht weigeren het verzoek te autoriseren. Probeer dit niet thuis, want je API-sleutel staat in de Authorization-header. Deze taal/bibliotheekfunctie voelde voor mij onveilig.

Java

I’ve not written any serious Java before, but it was easy to piece this together by following the general approach used in the SparkPost bibliotheek for other GET calls.

Incidentally, using VS Code as my editor / debugger worked really well for all the languages here, giving me syntax highlighting, debugger stepping / variables viewing etc. De InputStreamReaderand BufferedReaderconstructs are similar to (and I assume were copied by) Go.

C / C++

This was a trip down memory lane, as I wrote a lot of C code in the 1990s, some still running deep in telecoms networks somewhere. As the geschiedenis van C predates the modern Web, it’s not surprising that library support is a manual task. We need to download (and compile) a recent version of Libcurl, linking to an OpenSSL library – see the README for actual steps.

Dit voelt als veel werk in vergelijking met moderne talen, vooral wanneer Go (of Lua, of Python, of een van de andere) snel genoeg zijn voor dit soort taken.

De other thing I had forgotten, despite bearing the scars from previous battles, is the scariness of memory allocation! To keep the example simple, I preallocated the URL string length as 1024 characters, and bounds-checked the email address length (using strlen) before we concatenate into it (using strcat).

We behandelen de Autorisatiestring met een samengevoegde API-sleutel op dezelfde manier ... ook al weten we dat een geldige API-sleutel nooit te lang zal zijn ... dat is geen bescherming! Gebruikersinvoer van een omgevingsvariabele kan van alles zijn. Je moet defensief programmeren.

A more sophisticated developer might use mallocinstead of stack variable allocation, and calculate just how long the joined strings need to be. Having to think about this extra complexity gave me a pijn in de diodes in mijn linkerzij...; it reminded me of the risks that C programmers run every day, trying to avoid buffer overruns and unexpected side-effects. Which brings us to ..

Lua

Lua is known for its easy coexistence alongside a body of C code, and here at SparkPost, we gebruikte Lua uitgebreid for Policy customisations inside our Momentum on-premises MTA. You can also use it as a stand-alone scripting language, and it’s pretty nice for that, too.

With Lua 5.3 and the luarocks package manager, we use libraries luasocket and luasec. Showing its C integration heritage, we link to our local OpenSSL library. The luarocks install process calls the gcc compiler (or whatever C compiler you are using), so adding new libraries takes a while.

The Lua code is quite simple. The characters — mark comments.  The function https.request provides meerdere terugkeerwaarden (a bit like Python and Go). String concatenation is done with the operator  .. (instead of + in Python).

The response body from this call is handled with the “ltn12” module – see here. That enables efficient handling of data that could be returned in multiple “chunks”. As that article explains:

De table factory creëert een sink die alle verkregen gegevens opslaat in een tabel. De gegevens kunnen later efficiënt worden samengevoegd tot een enkele string met de bibliotheekfunctie table.concat.

Ons voorbeeld voegt alleen tabel t samen en drukt het af; u zou een filter kunnen gebruiken om meer bewerkingen uit te voeren.

Perl

While Perl is famous for its one liners, this is not one of them.  Perl was designed for very fast document search and modification, but is actually capable of so much more.  I once wrote an entire Inventory control suite in Perl.  Go figure.   A n y w a y…

This script makes use of LWP::UserAgent and HTTP::Request and optionally the JSON and Data::Dumper packages depending on how you want to see the output. As with all the other scripts on this page, you should pre-set an environment variable SPARKPOST_API_KEYto your generated API key that includes the Recipient Validation function. This script hard codes $recipient = ‘test@gmail.com’ but you can easily add command-line input or consume from a file.

After all the variables are populated, we load an HTTP:Request with GET parameters and send it to the LWP:UserAgent.  The resulting “message” is the result of the email validation test as an array.  You can use JSON and DUMPER to display the result or just pass the array on for additional processing.

VB.net

Visual Basic is not visual and it is not basic (IMHO), but it is #6 on the TIOBE taalindex so here we go.

There are other ways to do this, but the easiest path to success is to use the Visual Studio SDK in a Windows platform. Fire up Visual Studio, start a new project and select Visual Basic, then select console.app.  Be sure to use the VB version not the C# version – it is easy to miss that in the SDK.

At this point you can edit lines manually or copy/paste the code vanaf hier into VS and save a bunch of time. In order to make this code work, you need to add a Windows environment variable.  The easiest way to do this is to open a command prompt and use setx.exe like this: 

C:\Users\me>setx SPARKPOST_API_KEY  "142<redacted<redacted>c531c3"

In Windows 10 wordt dit toegepast op uw gebruikersomgeving, maar is het niet onmiddellijk beschikbaar in de huidige opdrachtsessie, dus testen met een "set" zal niet werken, maar het zal beschikbaar zijn voor de code. Als u de in de repo opgenomen code bouwt en uitvoert, ziet u het validatieresultaat.

Roest

Rust is a language for systems and web-services programming that is focused on performance, safety and concurrency. As Wikipedia says, Rust has been the “most loved programming language” in the Stack Overflow Developer Survey since 2016.

The Rust code in onze Github repo uses the reqwest library with tokio async, similar to this example from the Rust cookbook. (That’s not a typo, the reqwest library name is spelled like that). We’ve included a cargo package manager configuratiebestand, so you can build and run with:

cd rust_ontvanger_validatie lading uitvoeren

Dit compileert het pakket in uitvoerbare code, en voert het uit:

Voltooid dev [unoptimized + debuginfo] target(s) in 0.10s Running `target/debug/rust_recipient_validation` Status: 200 OK Body: : (etc)

The code uses std:envto read the SPARKPOST_API_KEY environment variable. A match clause handles the case where the key is undefined. If all is well, a new reqwest::Client is created and an async call issued, followed by an .wacht? (see here). Async, rather than the simpler blocking call, seems to be needed to set request headers. Response body text is read with a second .wacht?, as per dit voorbeeld.

Summary

In dit artikel hebben we de Recipient Validation codevoorbeelden in vele talen doorgenomen. Hier is ons verzoek aan jou.

Let us know if you think we missed your favorite language. We may not have as many examples as Het Fibonacci Project, but we’d love to add some more. Also, if you think our examples can be improved, let us know!