IMAP and SMTP settings of 71 mail providers, probed live

What the probe found

Every provider

Sorted by name. Each provider links to its setup guide for Claude, ChatGPT and other MCP clients.

How it was measured

• Hosts and ports come from the Thunderbird ISPDB where it lists the provider, and from the provider’s own documentation otherwise. The settingsSource field says which.
• Each host was reached over TLS and the certificate checked against that exact hostname, so every host listed here answered under the name we publish.
• We read the IMAP greeting and CAPABILITY, and the SMTP EHLO reply. We never logged in and never touched a mailbox.
• Extensions that servers list only after login, such as MOVE, IDLE and SPECIAL-USE, are left out. A pre-login probe would report them as missing on servers that support them.
• Only providers whose servers answered are included. Mailboxes we reach through an API rather than IMAP, such as Outlook.com through Microsoft Graph, are covered in the feature matrix instead.

Feature support per provider · All setup guides

Fields

The JSON and CSV carry the same fields in this order. In the CSV, lists are space-separated inside one cell.

slug

Stable identifier, also the /connect/<slug> page.

name

Provider name.

domain

Main consumer address domain, or empty for hosts that serve your own domain.

category

consumer, business, hosting, cpanel, privacy, isp, regional or selfhost.

imapHost

IMAP server hostname. The certificate was validated against it.

imapPort

IMAP port.

imapSecurity

tls (implicit TLS) or starttls.

imapAuth

SASL mechanisms the IMAP server advertises before login (AUTH=).

saslIr

Whether the server advertises SASL-IR (credentials sent with the AUTHENTICATE command in one round trip).

smtpHost

SMTP submission hostname.

smtpPort

SMTP submission port.

smtpSecurity

tls (implicit TLS) or starttls.

smtpAuth

SASL mechanisms in the EHLO reply. Empty when the server only lists them after STARTTLS.

smtpMaxSizeMb

SMTP SIZE limit in MiB, for the whole encoded message. Attachments grow by about a third in base64.

oauthAdvertised

Whether IMAP advertises XOAUTH2 or OAUTHBEARER. Advertised is not the same as open to third-party apps.

settingsSource

Where the hosts and ports came from: ispdb+probe (Thunderbird ISPDB) or vendor+probe (vendor documentation).

probedOn

Date of the probe (YYYY-MM-DD).

page

Setup guide for connecting this provider to an AI assistant.

Use and cite

Free to use, copy and build on under CC BY 4.0, with credit. Settings drawn from the Thunderbird ISPDB are also available there under MPL 2.0. Found something wrong? Write to hello@mcpemails.com and we will re-check it. CC BY 4.0

MCPEmails, "IMAP and SMTP provider compatibility dataset", probed 2026-08-31. https://mcpemails.com/docs/providers/data