SMTP vs HTTP MailSlurp: A comparison of email protocols and services.

MailSlurp offers two types of inbox: or . Both act like regular email addresses - they can send and receive emails and attachments on demand. They differ in which mail server processes inbound emails and whether they can be accessed in clients like Outlook, Mail, and Exchange.

HTTP inboxes

HTTP inboxes are the default inbox type. They use AWS SES to process emails and are best used for test email accounts and internal email addresses. They are fast and reliable but may not support some legacy email clients such as Outlook. Please use SMTP inboxes for public facing email addresses or if you wish to have traditional SMTP IMAP accesses.

SMTP inboxes

SMTP inboxes use a custom SMTP mail server running at and an IMAP server running at . SMTP inboxes supports a wide range of email clients and allow you to use MailSlurp with Outlook, Gmail etc. plus in applications using SMTP/TCP clients. SMTP inboxes are best used for public facing email accounts that receive emails from customers and external contacts or for advanced access using .

For a list of POP3, IMAP, and SMTP ports and hosts see the MailServer guide.

Custom domain support

To use custom domains with MailSlurp create a domain that is either or type. The domain type determines the type of inbox that can be used with it. See the domain creation guide for more information or the SMTP IMAP access guide.

Diagnose email receiving

If your inbox is not working as expected or is not receiving emails please refer to the guide on diagnosing email receiving.