Keep legacy email clients working with Exchange Online.
lette.io proxies IMAP and SMTP traffic from legacy email clients and devices, while handling modern authentication with Exchange Online securely in the background.
lette.io proxies IMAP and SMTP traffic from legacy email clients and devices, while handling modern authentication with Exchange Online securely in the background.
A simpler, more secure way to support legacy email clients — without running your own mail servers.
lette.io keeps all email fully inside Microsoft 365 while enabling legacy clients and devices to authenticate and communicate securely using IMAP and SMTP.
All email is sent, received, stored, and audited in Microsoft 365. lette.io modernizes access and authentication without replacing your system.
Avoid running secondary mail servers or custom IMAP proxies. No patching, monitoring, backups, or capacity planning.
Works with your existing tenant, identities, and mail flow. No migrations or mailbox moves required.
Compatible with legacy email apps, printers, scanners, and embedded devices using SMTP and IMAP, including implicit TLS and STARTTLS.
SMTP support was introduced proactively to align with Microsoft’s Basic Auth deprecation.
Retention, journaling, eDiscovery, audit logs, and DLP continue to function normally because email never leaves Microsoft 365.
Get production-ready in minutes instead of engineering and maintaining custom SMTP relays or IMAP proxy infrastructure.
lette.io is not only for single-company deployments. It also fits managed service providers and IT partners who need a repeatable way to support legacy email access across multiple customer environments.
Instead of solving the same SMTP and IMAP compatibility problem tenant by tenant, standardize the approach while keeping every customer's Microsoft 365 environment, mail flow, and compliance boundary intact.
Use the same Microsoft 365-based access model for every managed customer instead of building and maintaining one-off SMTP relay or IMAP proxy workarounds.
Mail stays inside each customer's Microsoft 365 tenant. lette.io adds secure legacy access without forcing mailbox migration or handing message storage to a third party.
One billing account can adopt and manage multiple customer tenants while each tenant keeps its own mailbox selection, permissions, and Microsoft 365 configuration context.
When printers, scanners, line-of-business apps, or legacy mail clients keep showing up, lette.io gives your team a repeatable operational model instead of another custom exception.
Mailbox volume discounts are calculated across all active subscribed mailboxes on the same billing account, which is a better fit for MSP-style customer portfolios.
If you manage many tenants, need a dedicated setup, or want a reseller arrangement, we can work with you on an operating model that fits your service offering. Free NFR access can also be provided on request.
Each tenant starts with a 14-day free trial. The base price is $7.00 per mailbox / month. Volume discounts apply across all active subscribed mailboxes on the same billing account, even when they are split across multiple tenants.
Need pricing for a larger number of mailboxes, a dedicated proxy instance, or a reseller setup? Contact us.
01
Grant lette.io access to authenticate users securely in your Microsoft 365 environment.
02
Select which mailboxes should be accessible through legacy IMAP and SMTP clients.
03
Point email apps, printers, or scanners to lette.io — Exchange Online stays the system of record.
Start your free 14-day trial — no setup fees, cancel anytime.