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Now You Can Send and Receive Secure Emails
on Any Device

We are pleased to announce you that the implementation of SMTP/IMAP in the SFLetter.com email service has been completed.

This feature enables users send and receive secure email messages after a simple setup procedure on any device (PC, smartphone, tablet, etc.) and operating system, using an usual email client, for example, Microsoft Outlook or built-in iOS email client.

What is IMAP?

IMAP is a special protocol that opens up expansive opportunities for users to work with a SFLetter.com account. An email client that uses this protocol has access to the storage of emails on the server in such a way as if emails are located on a recipient's device. This protocol allows you to receive secure email messages on any device if you put the necessary data of your mailbox and the SFLetter.com server into email client settings.

IMAP (receiving secure emails) is available to all users for free.


Server name - sfletter.com
Port IMAP - 993 SSL (secured, you need to install a special certificate at the request of the email client)
or 143 - unsecured, but easy to configure

What is SMTP?

SMTP is an email transfer protocol that supports sending of emails from a remote device. Stripped of fine words, now you can take your smart phone and send a secure message without having to login into your SFLetter.com account through a browser.

SMTP for outgoing protected and unprotected emails is available only for users of Business and Premium accounts. Learn more about accounts.


Port SMTP - 465 SSL (secured, you need to install a special certificate at the request of the email client)
or 25 - unsecured, but easy to configure.

Username without SFLetter.com domain.

Supported operating systems: all*.

Supported email clients: all.

* Protected emails can be opened on devices under Windows, Android, iOS, and macOS.

Additional settings for email clients on desktop operating systems

In some cases, you may need to additional configure an e-mail client, for example, the Bat.

In the settings for sending and receiving messages, you must select Secure to dedicated port (TLS).
SMTP: select SMTP Authentication (RFC-2554) as standard for receiving mail.
IMAP: without changes.

How to send secure emails via SMTP?

If you want to send an email message with a protected body and attachment you need to type in the subject line the tag [p]. For example, The tasks for the week [p].

If you want to send email message and protect only an attachment you need to type the tag [pa] in the subject line .

Please note that sending secure messages via SMTP doesn't work if you use a test Premium account (protection against spam). All functional features will be available only after the payment. Or contact support team

If you have any additional questions about IMAP and SMTP, please email us.