…ls (javiereguiluz)

This PR was squashed before being merged into the 2.7 branch (closes #7115).

Discussion
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Better explain the most common problems when testing emails

Testing emails is simple but in the past I've suffered lots of problems related to this. In fact, a few minutes ago I fixed a long standing wrong test thanks to this comment about page redirections and collectors: symfony/symfony#20282 (comment)

I propose to create a new mini section to better explain the problems that you may face when testing emails.

Commits
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c2e0608 Better explain the most common problems when testing emails

* 2.7: (31 commits)
  fix a typo
  [#7115] fix headlines
  Better explain the most common problems when testing emails
  Clarify the mappings that require no method prefix.
  Make some long lines shorter to fit our soft limit of 80 chars per line
  Microsoft Azure update step by step article and screenshots for the new Microsoft Azure Portal
  Minor rewords in the text and the code example
  Update questionhelper.rst
  Add docs about console question answer normalizing.
  [#7105] add XML and PHP service config examples
  Minor rewordings
  When talking about generic responses, don't spell it as Response (which is a Symfony class)
  xabbuh review
  fix typo
  fix yml marker to yaml
  add documentation about access denied handler
  Update outdated link to AWS ELB security groups
  Added missing comma
  Reworded the caution about open redirects
  Warn user about open redirects
  ...

* 2.8: (37 commits)
  fix a typo
  [#7115] fix headlines
  Better explain the most common problems when testing emails
  Clarify the mappings that require no method prefix.
  Make some long lines shorter to fit our soft limit of 80 chars per line
  Microsoft Azure update step by step article and screenshots for the new Microsoft Azure Portal
  Minor rewords in the text and the code example
  Update questionhelper.rst
  Add docs about console question answer normalizing.
  [#7105] add XML and PHP service config examples
  Minor rewordings
  When talking about generic responses, don't spell it as Response (which is a Symfony class)
  xabbuh review
  fix typo
  fix yml marker to yaml
  add documentation about access denied handler
  Update outdated link to AWS ELB security groups
  Added missing comma
  Reworded the caution about open redirects
  Warn user about open redirects
  ...

* 3.1: (41 commits)
  fix a typo
  [#7115] fix headlines
  Better explain the most common problems when testing emails
  Clarify the mappings that require no method prefix.
  Make some long lines shorter to fit our soft limit of 80 chars per line
  Microsoft Azure update step by step article and screenshots for the new Microsoft Azure Portal
  Minor rewords in the text and the code example
  Update questionhelper.rst
  Add docs about console question answer normalizing.
  [#7105] add XML and PHP service config examples
  Minor rewordings
  When talking about generic responses, don't spell it as Response (which is a Symfony class)
  xabbuh review
  fix typo
  fix yml marker to yaml
  add documentation about access denied handler
  Update outdated link to AWS ELB security groups
  Added missing comma
  Reworded the caution about open redirects
  Warn user about open redirects
  ...