Nextcloud is capable of sending password reset emails, notifying users of new file shares, changes in files, and activity notifications. Your users configure which notifications they want to receive on their Personal pages.

Nextcloud does not contain a full email server, but rather connects to your existing mail server. You must have a functioning mail server for Nextcloud to be able to send emails. You may have a mail server on the same machine as Nextcloud, or it may be a remote server.

To access the setup page below log in with an admin account. Click on your avatar in the top right, and then click Settings. On the left side under Administration and click Basic settings.


With the wizard, connecting Nextcloud to your mail server is fast and easy. The wizard fills in the values in config/config.php, so you may use either or both as you prefer.

The Nextcloud Email wizard supports three types of mail server connections: SMTP, qmail, and Sendmail. Use the SMTP configurator for a remote server or Sendmail when your mail server is on the same machine as Nextcloud.


The Sendmail option refers to the Sendmail SMTP server and any drop-in Sendmail replacement such as Postfix, Exim, or Courier. All of these include a sendmail binary, and are freely-interchangeable.

Configuring an SMTP server

You need the following information from your mail server administrator to connect Nextcloud to a remote SMTP server:


There were changes to the 3rd party mailer library in Nextcloud 26:

  • STARTTLS cannot be enforced. It will be used automatically if the mail server supports it. The encryption type should be set to ‘None/STARTTLS’ in this case. See here for an example on how to configure self signed certificates.

  • NTLM authentication for Microsoft Exchange is not supported by the new mailer library. Try using basic authentication instead.

  • Encryption type: None/STARTTLS or SSL

  • The From address you want your outgoing Nextcloud mails to use

  • Whether authentication is required

  • Authentication: when authentication is required, the underlying mailer will try the following authentication methods in the order they’re listed:

    • CramMd5

    • Login

    • Plain

    • XOAuth2

  • The server’s IP address or fully-qualified domain name and the SMTP port

  • Login credentials (if required)


The overwrite.cli.url parameter from config.php will be used for the SMTP EHLO.

Your changes are saved immediately, and you can click the Send Email button to test your configuration. This sends a test message to the email address you configured on your Personal page. The test message says:

If you received this email, the settings seem to be correct.

a safe home for all your data

Configuring Sendmail/qmail

Configuring Sendmail or qmail requires only that you select one of them instead of SMTP, and then enter your desired return email address.

In most cases the SMTP option is best, since you will be able to control all of your mail server options in one place, in your mail server configuration then.

Using email templates

We designed a mechanism that generates emails which follow the theming settings and look the same in all the different email clients out there.


If, for some reason, you need text-only emails, consider simply configuring this on the client side or let the receiving (or even sending) mail server drop the HTML part. Note that there is no security impact from sending HTML emails, just from displaying them and thus any security risk can only be mitigated by disabling showing HTML on the client (or removing the HTML part in the mail server).

Modifying the look of emails beyond the theming app capabilities

You can overwrite templates by writing a class that implements the template interface (or extends it to not need to copy over everything). Easiest way is to then put this class into an app and load it so you do not need to patch it on every update.

This is the interface of the class that needs to be implemented:

That is the implementation that could be extended and used to see how it works:

An example from a GitHub issue:

  1. Look at the source code of extended class OC\Mail\EMailTemplate::class

  2. Then override what you need in your own OC\Mail\EMailTemplate::class extension


Let’s assume that we need to override the email header:


namespace \OCA\MyApp;

use OC\Mail\EMailTemplate;

class MyClass extends EMailTemplate
   protected string $header = <<<EOF
      <table align="center" class="wrapper">
            // your theme email header modification
  1. Then in config/config.php change mail_template_class to your class namespace:

    'mail_template_class' => 'OCA\\MyApp\\MyClass',

You will find a detailed step by step guide in our support portal.

Setting mail server parameters in config.php

If you prefer, you may set your mail server parameters in config/config.php. The following examples are for SMTP, Sendmail, and Qmail.


If you want to send email using a local or remote SMTP server it is necessary to enter the name or IP address of the server, optionally followed by a colon separated port number, e.g. :425. If this value is not given the default port 25/tcp will be used unless you change that by modifying the mail_smtpport parameter.

"mail_smtpmode"     => "smtp",
"mail_smtphost"     => "smtp.server.dom:425",


"mail_smtpmode"     => "smtp",
"mail_smtphost"     => "smtp.server.dom",
"mail_smtpport"     => 425,

If a malware or SPAM scanner is running on the SMTP server it might be necessary that you increase the SMTP timeout to e.g. 30s:

"mail_smtptimeout"  => 30,

If the SMTP server accepts insecure connections, the default setting can be used:

"mail_smtpsecure"   => '',

The connection will be upgraded automatically via STARTTLS if the SMTP server supports it.

If required by the SMTP server, a secure SSL/TLS connection can be enforced via the SMTPS protocol which uses the port 465/tcp:

"mail_smtphost"     => "smtp.server.dom:465",
"mail_smtpsecure"   => 'ssl',

And finally it is necessary to configure if the SMTP server requires authentication, if not, the default values can be taken as is.

"mail_smtpauth"     => false,
"mail_smtpname"     => "",
"mail_smtppassword" => "",

If SMTP authentication is required you have to set the required username and password.

"mail_smtpauth"     => true,
"mail_smtpname"     => "username",
"mail_smtppassword" => "password",


If you want to use the well known Sendmail program to send email, it is necessary to have an installed and working email system on your *nix server. The sendmail binary (/usr/sbin/sendmail) is usually part of that system. Nextcloud should be able to send email out of the box.

"mail_smtpmode"     => "sendmail",
"mail_smtphost"     => "",
"mail_smtpport"     => 25,
"mail_smtptimeout"  => 10,
"mail_smtpsecure"   => "",
"mail_smtpauth"     => false,
"mail_smtpauthtype" => "LOGIN",
"mail_smtpname"     => "",
"mail_smtppassword" => "",


If you want to use the qmail program to send email, it is necessary to have an installed and working qmail email system on your server. The qmail binary installed on your server will then be used to send email. Nextcloud should be able to send email out of the box.

"mail_smtpmode"     => "qmail",
"mail_smtphost"     => "",
"mail_smtpport"     => 25,
"mail_smtptimeout"  => 10,
"mail_smtpsecure"   => "",
"mail_smtpauth"     => false,
"mail_smtpauthtype" => "LOGIN",
"mail_smtpname"     => "",
"mail_smtppassword" => "",

Send a test email

To test your email configuration, save your email address in your personal settings and then use the Send email button in the Email Server section of the Admin settings page.


Enabling debug mode

If you are unable to send email, it might be useful to activate further debug messages by enabling the mail_smtpdebug parameter and temporarily setting your NC loglevel to DEBUG:

"mail_smtpdebug" => true,
"loglevel" => 0,

Be cautious setting your loglevel to DEBUG (0) since it’ll apply to everything occurring on your NC instance, not just email. And don’t forget to set it back to a more reasonable level when you’re done troubleshooting:

"mail_smtpdebug" => false,
"loglevel" => 2,


Immediately after pressing the Send email button, as described before, several SMTP -> get_lines(): … messages appear on the screen. This is expected behavior and can be ignored.

Why is my web domain different from my mail domain?

The default domain name used for the sender address is the hostname where your Nextcloud installation is served. If you have a different mail domain name you can override this behavior by setting the following configuration parameter:

"mail_domain" => "",

This setting results in every email sent by Nextcloud (for example, the password reset email) having the domain part of the sender address appear as follows:

How can I find out if an SMTP server is reachable?

Use the ping command to check the server availability:

ping smtp.server.dom
PING smtp.server.dom (ip-address) 56(84) bytes of data.
64 bytes from your-server.local.lan ( icmp_req=1 ttl=64

How can I find out if the SMTP server is listening on a specific TCP port?

The best way to get mail server information is to ask your mail server admin. If you are the mail server admin, or need information in a hurry, you can use the netstat command. This example shows all active servers on your system, and the ports they are listening on. The SMTP server is listening on localhost port 25.

# netstat -pant
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address   Foreign Address  State  ID/Program name
tcp    0      0*        LISTEN   4418/cupsd
tcp    0      0*        LISTEN   2245/exim4
tcp    0      0*        LISTEN   1524/mysqld
  • 25/tcp is unencrypted smtp

  • 110/tcp/udp is unencrypted pop3

  • 143/tcp/udp is unencrypted imap4

  • 465/tcp is encrypted submissions

  • 587/tcp is opportunistically-encrypted submission

  • 993/tcp/udp is encrypted imaps

  • 995/tcp/udp is encrypted pop3s

How can I determine if the SMTP server supports the SMTPS protocol?

A good indication that the SMTP server supports the SMTPS protocol is that it is listening on the submissions port 465.

How can I determine what authorization and encryption protocols the mail server supports?

SMTP servers usually announce the availability of STARTTLS immediately after a connection has been established. You can easily check this using the telnet command.


You must enter the marked lines to obtain the information displayed.

telnet smtp.domain.dom 25
Connected to smtp.domain.dom.
Escape character is '^]'.
220 smtp.domain.dom ESMTP Exim 4.80.1 Tue, 22 Jan 2013 22:39:55 +0100
EHLO your-server.local.lan                   # <<< enter this command
250-smtp.domain.dom Hello your-server.local.lan [ip-address]
250-SIZE 52428800
250-AUTH PLAIN LOGIN CRAM-MD5                 # <<< Supported auth protocols
250-STARTTLS                                  # <<< Encryption is supported
250 HELP
QUIT                                          # <<< enter this command
221 smtp.domain.dom closing connection
Connection closed by foreign host.

How can I send mail using self-signed certificates or use STARTTLS with self signed certificates?

To disable peer verification or to use self signed certificates, add the following to your config/config.php:

"mail_smtpstreamoptions" => array(
    'ssl' => array(
        'allow_self_signed' => true,
        'verify_peer' => false,
        'verify_peer_name' => false

All emails keep getting rejected even though only one email address is invalid.

Partial sending, i. e. sending to all but the faulty email address is not possible.


Immediately after pressing the Send email button, as described before, several SMTP -> get_lines(): … messages appear on the screen. This is expected behavior and can be ignored.