* explicitly decide on using TLS for mail connections

* explicitly decide on using TLS for mail connections

* keep compatibility

* Add support for extra sendmail arguments

* Sendmail args to exec.command should be a list

* Add go-shellquote package

* Use go-shellquote lib for parsing Sendmail args

* Only parse if sendmail is configured

* Fix sending mail with a non-latin display name. #2102

Signed-off-by: Rémi Saurel <contact@remi-saurel.com>

* Take into account the possibility that setting.MailService.From is in `name <email@address>` format. #2102

Signed-off-by: Rémi Saurel <contact@remi-saurel.com>

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* Send mails as HTML as default. Setting for send as plain text.
 * Add new option SendAsPlainText. remove EnableHTMLAlternative
 * Send HTML mails as default
 * Add html check if html2text should be performed

* Send only multipart or plain. Add deprication warning for ENABLE_HTML_ALTERNATIVE

* Still use ENABLE_HTML_ALTERNATIVE for backward compatibility

* Changed to not ignore html2text errors

This change corrects a few logging issues:

 * Standardized formatting errors with '%v'.
 * Standardized failure warning word usage.
 * Corrected an instance of using the standard log library when
   the gitea log library should be used instead.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* Implemented sendmail. This piggybacks on existing configuration to keep the change simple

* Changed privicy of new sendSMTP and sendSendmail functions

* Fixed Lint errors

* Seperated SMTP and sendmail into their own senders

* Making new structs private as they should not be used externally now

* Added sendmail setting to ini file

* Minor code cleanup

- Update import paths from github.com/go-gitea to code.gitea.io
- Fix import path for travis

See https://docs.travis-ci.com/user/languages/go#Go-Import-Path

* Do not write HTML in text/plain mail part

Fixes #2928

* Pass text/plain first, text/html second

* Do not send plain/text email if html2text failed (untested)

Also fix a possible race condition while install

- #1496: fallback plain text
- #1002: add date header
- #913: fix encoding of header

i've been missing a 'r' in previous, lol~

- fix delete user but repository watches are not decreased

New config keys in [mailer] section:
 - CERT_FILE: path to a certificate file.
 - KEY_FILE: path to a key file.

The User member of a message is not needed anymore.

The from that is send to the server, should always be the "system" from. This is also called the Bounce address http://en.wikipedia.org/wiki/Bounce_address

This lines got committed by accident. They do actually nothing, as SplitHostPort will give an error if port is not given.