One email API for Gmail, Outlook and anything with IMAP

Official OAuth for Gmail and Outlook, IMAP for everything else, and the same object model as every other channel Aux0 connects.

GmailOutlookiCloudFastmailZoho MailIMAP & SMTP
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In numbers

3ways inGmail, Outlook and plain IMAP
OAuthwhere the provider offers itNo credential reaches you
Draftsinto the user's own clientSo a human approves before it sends
1shape with messagingA Gmail thread and an IMAP thread match

Nylas covers more mail providers than we do. The reason to take email from us is a published price, your own OAuth client on every plan, and the sync state on a screen.

What you get

A Gmail thread in Aux0 with an attachment, an open-tracking badge and a draft awaiting review.

The mailbox, not a sending service

You work the user's own inbox: their threads, their folders, their drafts. Mail goes out from their address and lands in their sent folder. There is no shared IP pool and no deliverability to manage.

Drafts for a human to approve

Write into the user's own drafts folder and they review, edit and send from the client they already use. For anything an agent composes, this is the shape people actually turn on.

Replies that stay in the thread

Pass the message you are replying to and the provider threads it properly. A reply that starts a new thread is the most common way an integration annoys a recipient.

IMAP for the long tail

Self-hosted mail, regional providers, the legacy server nobody will migrate. The same endpoints, so supporting one is a settings row, not a branch.

The endpoints

The whole surface, on one screen

The same calls whichever provider the account is on. Full reference in the documentation.

GET/v1/threadsMail threads, with search and folder filters
GET/v1/emailsMessages, filtered by thread or folder
POST/v1/emailsSend, or reply in thread
POST/v1/emails/draftsWrite a draft into the user's own client
GET/v1/foldersFolders and labels, with their roles
GET/v1/emails/:id/attachments/:attachmentIdFetch attachment bytes

Against an email-only API

Nylas and its peers cover more mail providers than we do, and if the long tail is your requirement they are a reasonable choice. We publish our price, support your own OAuth client on every plan, and put the sync state where support can see it.

Against an email-only API

All six comparisons

Gmail and Outlook over OAuth

Aux0
Yes
Email-only
Yes

IMAP and SMTP

Aux0
Yes
Email-only
Yes

Drafts, folders and threading

Aux0
Yes
Email-only
Yes

Breadth of mail providers

They cover hundreds. We cover Gmail, Outlook and IMAP.

Aux0
Partial
Email-only
Yes

Bring your own OAuth client on every plan

Aux0
Yes
Email-only
Partial

Sync state visible per account

Aux0
Yes
Email-only
No

One object model across mail and messaging

Aux0
Yes
Email-only
No

One bill and one auth flow

Aux0
Yes
Email-only
No

The providers

Gmail

Google OAuth, mailbox read and send, threads and labels

Outlook

Microsoft 365 and personal Outlook over Graph

iCloud

iCloud Mail, Calendar and Contacts with an app-specific password

Fastmail

Fastmail mailboxes, with JMAP on the roadmap

Zoho Mail

Zoho mailboxes through the same unified endpoints

IMAP & SMTP

Any mail server, including the ones that will never ship OAuth

Questions

What is a unified email API?

One set of endpoints that reads and sends across several mail providers and returns the same shape for each. Aux0 covers Gmail and Outlook through their own OAuth consent screens and everything else over IMAP, so your code does not know which provider a mailbox is on.

Is Aux0 a bulk email sending service?

No. Aux0 works the mailbox a user already has, so mail goes out from their address with their reputation. If you need to send a million messages from your own domain, you want a sending service such as Postmark or SES instead — a different product solving a different problem.

Why not use an email-only API?

If the long tail of regional providers is your requirement, do: Nylas and its peers support more than we do. The reason to take email from us is a published price, your own OAuth client on every plan, and sync state your support team can read without filing a ticket.

Do you need restricted Gmail scopes?

Only the ones your enabled capabilities require. Reading mail needs a restricted scope, and any app requesting one needs Google's verification before it leaves testing — that is true of every vendor. Aux0 requests the narrowest set Google offers for what you turn on.

One connected account, free, for as long as you want it

Enough to build the whole integration before you pay for anything.

Start buildingHow Aux0 connects accounts