Here are server info for email clients.

Protocol    server    port    security
IMAP   993   SSL
SMTP   587   StartTLS

For now we have two MX servers for incoming messages.

Type   server    location
Primary   Durham, US
Secondary   Limburg, NL

The mail server is run totally by open source software. Follows are software info.

Software    version
Ubuntu    20.04.5
Postfix   3.4.13
OpenDKIM    2.11.0
policyd-spf    2.9.2
Snappymail    almost the latest version
Certbot   1.31.0
Apache    2.4.41

Here are some limits you may want to know.

- Disk quota limits to 200 MB
- Message size limits to 20 MB
- Attachment size from webmail limits to 5 MB
- Sending amount limits to 10 mails by minutes, 150 mails by days

The following actions may lead to your account and/or IP being banned.

- Sending spam
- Conducting any activity which breaks the laws
- Using your Email address to abuse other services
- Other circumstances which aren't listed here

For privacy care we promise that:

- Never scan users' email
- Never sell your data to others
- Do not store users' personal data
- Do not keep track of logs
- Do not use cookies (except webmail)

We have daily automated testing for delivery capacity. The follows are providers we have covered.

- Gmail
- Outlook/Hotmail
- Yahoo
- iCloud
- ATT/Currently
- Fastmail/Pobox
- GMX/
- T-Online
- Vodafone
- ProtonMail
- Yandex
- Orange

We are based on open source. As feedback we would like to share our key code to open source community. For example, the methods we use to manage user accounts and passwords have been uploaded to MetaCPAN. If you examine the following code, you will see that we don't log any private data of users.

We also wrote a perl client for sendmail using OpenMbox or any other smtp servers. And an auto test module was included for delivery capacity.