API Features Overview

What can you do with the SMTP2GO API?

The API has many uses including sending emails or SMS messages, retrieving your account data and managing your account. Below is an overview of what you can do programmatically with the API.


There are two ways to send emails through the API; Standard Email (/email/send) and MIME Email (/email/mime).

With the /email/send endpoint, you pass us all of the components of an email, such as the sender, subject, body and recipient as a JSON Object. We then create the email and send it.

Alternatively, you may send an email composed as a MIME string. This can be done using a MIME library in your programming language of choice, before sending this to SMTP2GO via the /email/mime endpoint. SMTP2GO will use this exact MIME string to send the email.



Customers on paid-level plans can send SMS messages to single or multiple recipients, up to a maximum of 100 destination addresses at a time. You can also view received SMS messages if a recipient responds. Sending SMS messages does incur additional charges. Further additional SMS settings are available within the SMTP2GO App.


Account Activity

Search email events such as bounces, opens and unsubscribes in your account. You can search by sender search_sender, recipient search_recipient and a range of other parameters.


Allowed Senders

Restrict sending via your account either based on the sender email address or domain using the ‘Restrict Senders’ feature located on the “Settings > Sending Options > Restrictions” section of the App. After enabling Restrict Senders, you create a list of addresses and/or domains. On the Restrict Senders section, you can set it so the list consists of ‘allowed’ senders or you can set it so the listed addresses or domains are ‘not allowed’ to send through the account. The feature can be used as an allowlist or a blocklist.


SMTP Users

An SMTP User is a username and password combination used to authenticate our servers when sending via SMTP. Standard authentication via username and password is expected by default.

You can optionally choose to set up an SMTP User for each sender, or for different devices/setups that intend to send emails through your account as this provides separation. For each SMTP User, you can optionally enable an unsubscribe footer, open tracking, click tracking, user status, email archiving (if on a paid plan), email auditing, bounce notifications and set a rate (speed) limit.


Sender Domains

A Sender Domain is a domain name from which you send emails. Verify a Sender Domain to enable SPF and DKIM to be properly handled, and to allow sending from any address at the domain.


Single Sender Emails

If it is not possible for you to verify a sender domain, you can authorize an individual address to be able to send. This is only recommended if you cannot update the DNS of your domain, as emails won’t be DKIM-signed with your domain.



Retrieve account statistics to help monitor your deliverability, bounce rate, account status, monthly usage and much more.


Email Archiving

Email Archiving is available to customers on paid-level plans and allows the ability to store emails (content, attachments and delivery records) for 1-5 years. Archiving does incur additional charges.



Subaccounts are available to customers with paid-level plans and are designed for agencies/MSPs or resellers with customers of their own, who wish to keep their customers’ data completely separate from each other.



Your account stores a list of email addresses and domains that are automatically suppressed (blocked) from receiving emails due to hard bounces, spam complaints, unsubscribes and those that are manually added. With the API, you can add, view and remove suppressions.


IP Allowlist

The IP Allowlist feature improves account security by allowing you to restrict sending to be from allowed IP addresses only. If enabled, sending from IPs that are not listed will be blocked.



Manage email templates within your account to be integrated and personalized when sending via the API.



Set up and manage Webhooks which allow SMTP2GO to notify your web service instantly when an event happens in your SMTP2GO account (e.g. be notified when an email bounces or if an email is opened).