IMAP and SMTP API for every mail server that will never ship OAuth
Host, port, credentials. The same endpoints as Gmail and Outlook, for the mail servers that will never have an OAuth app.
IMAP & SMTP
How an account links
- IMAP/SMTP
- emailList mail · Send mail · Drafts · Folders and labels · Threading · Attachments6
- platformWebhooks1
In numbers
7 capabilitiesWhat Aux0 does with IMAP & SMTP
7 capabilitiesAny mail server, including the ones that will never ship OAuth
Point Aux0 at a host, port and credentials and get the same unified mail API as Gmail and Outlook. This is the engine behind iCloud, Fastmail and Zoho, and it covers self-hosted mail, regional providers, on-premise Exchange and the long tail.
The customers an OAuth-only vendor turns away
Self-hosted mail, regional providers, a legacy server nobody will migrate. IMAP reaches them and the response shape is the same one your code already handles.
Credentials your product never sees
Host, port and password are entered on the hosted auth page, not in your product. For mail servers with no OAuth, this is the difference between holding a password and not.
Realtime where the server allows it
Aux0 uses IMAP IDLE where the server supports it and falls back to a short poll where it does not, so the webhook contract is the same either way.
- List mailPage through messages with search, label and date filters.
GET /v1/emails - Send mailSend a message, reply in thread, or forward one.
POST /v1/emails - DraftsCreate, update and delete drafts in the user's own mailbox.
POST /v1/emails/drafts - Folders and labelsList folders, and move or label a message.
GET /v1/folders - ThreadingGroup messages into threads with a stable thread id.
GET /v1/emails?thread_id= - AttachmentsUpload outbound attachments and fetch inbound ones.
GET /v1/emails/:id/attachments/:attachmentId
Platform
- WebhooksSigned delivery of every event, with replay and a dead letter queue.
POST /v1/webhooks
How an account is linked
AuthIMAP/SMTP
Host, port and credentials for a mail server. For self-hosted mail, regional providers and the long tail that will never ship an OAuth app.
Whichever method a provider uses, your users complete it on a page Aux0 serves under your branding. You receive an account id and a webhook; no password, QR scan or one-time code ever reaches your product. How hosted auth works.
What it is bought for
Use casesCustomers whose mail is self-hosted or on a regional provider
On-premise Exchange that no hosted API reaches
Migrating off a legacy mail integration without rewriting the consumer
What you should know first
LimitsThe constraints, before you commit
These are the provider's rules, not ours. We would rather you read them now than discover one in production.
Realtime depends on the server supporting IMAP IDLE; Aux0 falls back to a short poll.
Threading is computed by Aux0 on servers that expose no thread id.
Google accounts are not connected this way — they use the Gmail API.
Questions
FAQWhat mail servers does the IMAP connector work with?
Anything speaking IMAP for reads and SMTP for sends, which in practice is every mail server. It is the connector for self-hosted mail, regional providers and anything that will never publish an OAuth app.
Is IMAP realtime?
Where the server supports IMAP IDLE, yes, and new mail reaches your webhook within seconds. Where it does not, Aux0 falls back to a short poll. Your side of the contract is identical either way.
What does IMAP not support?
Open tracking is unreliable on servers that strip remote content, and some servers have no stable thread identifier, so threading is reconstructed from headers. Everything else behaves as Gmail and Outlook do.
Next
RelatedConnect IMAP & SMTP on the free plan
One connected account, every provider, forever. It is enough to build the whole integration before you pay for anything.