[REM] email marketing: remove all docs (#877)

These pages document very straightforward screens and flows users can easily figure out without dedicated documentation. Besides, those screens are frequently reworked, requiring to maintain the related pages closely. This commit then removes low-value pages to reduce the technical debt and allow focusing on actually useful documentation pages.
Docs removed:
- mailing_lists.rst
- manage_unsubscriptions.rst
- send_emails.rst

applications.rst

@@ -71,7 +71,6 @@ Applications
    ecommerce
    helpdesk
    live_chat
-   email_marketing
    sms_marketing
    marketing_automation
    survey

email_marketing.rst

@@ -1,10 +0,0 @@
-:banner: banners/email_marketing.png
-
-================
-Email Marketing
-================
-
-.. toctree::
-   :titlesonly:
-
-   email_marketing/overview

email_marketing/overview.rst

@@ -1,10 +0,0 @@
-========
-Overview
-========
-
-.. toctree::
-   :titlesonly:
-
-   overview/send_emails
-   overview/mailing_lists
-   overview/manage_unsubscriptions

email_marketing/overview/mailing_lists.rst

@@ -1,51 +0,0 @@
-=======================
-Work with Mailing Lists
-=======================
-
-Mailing lists can be a goldmine for your company’s marketing department as they can provide leads
-for sales, focus groups for testing new products, and consumers to provide feedback on satisfaction,
-for example.
-
-Create mailing lists
-====================
-
-Go to :menuselection:`Mailing lists --> Mailing lists --> Create`. Enable the option *Is Public* to
-make the list visible for users when unsubscribing.
-
-.. image:: media/mailing1.png
-   :align: center
-   :alt: Mailing lists in Odoo Email Marketing
-
-Once your mailing list is created, you can manually add contacts clicking on *Create*. *Import* a
-list of contacts if you have it from a previous tool.
-
-Linking a mailing list to my website
--------------------------------------
-
-| Create a mailing list called Newsletter, as you use this strategy to advertise and communicate new
-  ideas to subscribers interested in listening.
-| Go to your *Website*, add a *Newsletter* block and choose the respective mailing list.
-
-.. image:: media/mailing2.png
-   :align: center
-   :alt: Mailing lists in Odoo Email Marketing
-
-Contacts
---------
-
-Under :menuselection:`Mailing Lists --> Mailing List Contacts` see a list of all contacts under all
-your mailing lists, and the ones you individually created here.
-
-.. image:: media/mailing3.png
-   :align: center
-   :alt: Mailing lists in Odoo Email Marketing
-
-Open a contact form to see or add different mailing lists to which the contact is or will be part of.
-
-.. image:: media/mailing4.png
-   :align: center
-   :height: 400
-   :alt: Mailing lists in Odoo Email Marketing
-
-.. seealso::
-   - :doc:`send_emails`

email_marketing/overview/manage_unsubscriptions.rst

@@ -1,47 +0,0 @@
-====================================
-Manage Unsubscriptions and Blacklist
-====================================
-
-It is best practice, and legally required, to allow recipients to unsubscribe from mailing lists
-as you do not want your audience to think that your company is using any tactics that are dishonest
-or spammy.
-
-Enable the Blacklist feature
-============================
-
-Go to :menuselection:`Configuration --> Settings` and enable the option *Blacklist Option when
-Unsubscribing*.
-
-.. image:: media/manage1.png
-   :align: center
-   :alt: Blacklist in Odoo Email Marketing
-
-Now, once the user clicks on the *Unsubscribe* link on your email, he is redirected to the
-following page:
-
-.. image:: media/manage2.png
-   :align: center
-   :height: 350
-   :alt: Blacklist in Odoo Email Marketing
-
-.. note::
-   After clicking on the unsubscribe button when using the test feature, you are sent to
-   an error page (*error 403 - Access Denied*). If you want to be sure the link is working properly,
-   create your mass mail and send it only to a personal email.
-
-In addition to having the option of unsubscribing from specific mailing lists, the user can also
-blacklist himself, meaning that he will not receive *any* more emails from you.
-
-.. note::
-   The mailing list has to be configured as *Public* in order to be visible for users.
-
-| Under :menuselection:`Configuration --> Blacklist`, blacklisted email addresses are shown.
-| When opening the record, as a *Log note*, a description-history is kept.
-
-.. image:: media/manage3.png
-   :align: center
-   :alt: Blacklist in Odoo Email Marketing
-
-.. seealso::
-   - :doc:`send_emails`
-   - :doc:`mailing_lists`

email_marketing/overview/send_emails.rst

@@ -1,86 +0,0 @@
-==========================================
-Send Emails Marketing and Manage Campaigns
-==========================================
-
-Emails allow you to effectively, and at a low cost, reach a large number of consumers while being
-able to customize your message in a way that resonates with them. It is measurable, and a
-call-to-action oriented channel.
-
-Choose the right target and create the message
-==============================================
-
-| Go to :menuselection:`Mailings --> Create`.
-| Choosing *Contacts* as *Recipients* (for example), allows you to add specifications to match
-  just certain contacts, filtering your target.
-
-.. image:: media/sendemails1.png
-   :align: center
-   :alt: Send mass mailing in Odoo Email Marketing
-
-.. note::
-   With a trial databases, you have a limit of 50 emails per day; on Odoo SH Cloud
-   Platform the limit is 200. There is a possibility to increase these numbers by contacting Odoo
-   Support. To contact Support, `click here <https://www.odoo.com/help>`_.
-
-Under *Mail Body*, choose a layout and make the modifications needed by dragging, dropping and
-double-clicking on content. Note that it is possible to start from scratch selecting the *blank*
-template option.
-
-.. image:: media/sendemails2.png
-   :align: center
-   :alt: Send mass mailing in Odoo Email Marketing
-
-| Under *Settings*, you can assign someone else as the responsible sender if you do not want it to
-  be you. To do so, change the email address used as the sender (*Send From*).
-| With the *Reply To* radio button, you can also choose to gather answers either on the respective
-  recipients’ records or on a specific email address. Note that this option is not available if you
-  target mailing contacts or contacts as recipients.
-
-.. image:: media/sendemails3.png
-   :align: center
-   :height: 400
-   :alt: Send mass mailing in Odoo Email Marketing
-
-Test, send or schedule a mailing
-================================
-
-.. image:: media/sendemails4.png
-   :align: center
-   :height: 350
-   :alt: Send mass mailing in Odoo Email Marketing
-
-| *Save*: the work is allocated in the *draft* column in the Kanban view. Modifications can be
-  made while being in this stage. The option *Discard* deletes the email.
-| Click on *Test* and send your message to one, or even multiple, test contacts to avoid errors.
-| *Send* triggers the email with the next run and put the work on the *queue* column in the
-  Kanban view.
-| *Schedule* allows you to choose a date and time, and puts the email in the *queue* column in
-  the Kanban view.
-
-.. note::
-   The daily limit is applied for **all emails** sent, in other words, throughout all applications.
-   Therefore, if at the end of the day you have remaining ones to be sent, note that they *will not*
-   be sent automatically the next day. You need to force that by opening the email and
-   clicking on *Retry*.
-
-Manage campaigns
-================
-
-| Go to :menuselection:`Configuration --> Settings` and enable *Mailing Campaigns*.
-| The campaign option is effective as it allows you to organize your marketing efforts and have a
-  centralized view of its metrics.
-| Go to *Campaign* and click on *Create* to start one.
-
-.. image:: media/sendemails5.png
-   :align: center
-   :height: 300
-   :alt: manage campaigns in Odoo Email Marketing
-
-.. note::
-   If you use the SMS and Social Marketing applications, as well as the Push Notification feature,
-   you see the option to create content for those channels. You also see the *Campaign*
-   menu within those applications. All of this is possible because the applications work integrated.
-
-.. seealso::
-   - :doc:`../../discuss/advanced/email_servers`
-