This is necessary so we don't add delivered-to addresses to the list of
addressee/collaborators.

necessary to avoid adding internal virtual address as a collaborator.

Store delivered-to email ID - giving us the ability to reply FROM specific
email address as opposed to the department's email.

This is needed to help us remove invalid characters set by some mail
clients.

Previously, the Delivered-To header was only used if the To header was not
found

Change z-index to overlay popup windows correctly

And allow plugin to support remotely-generated hashes for migration safety
verification

If a wrapped mail is sent, copy the Delivered-To header into the nested
message so it will be clear(er) how the mail arrived into the system. Also,
copy the Message-Id into the nested mail if there is none to help against
mails delivered repeatedly.

If an email arrives at the system and the system cannot determine why the
mail arrived (ie. a system email was not found in the To or Cc headers), the
recipients list should be maintained.

This is useful for generating collaborator lists as well as filtering by the
To and Cc (Addressee) headers.

Log every other third failed login attempt as a warning, instead of every
other request. This is necessary to avoid false warning since login page
attempts SSO via the backend.

Show ticket prview when a ticket number is clicked as opposed to ticket
view.
Add collaborator preview tab on ticket preview tool tip.

07fec4c4 introduced the ability to receive
and process messages forwarded as a message/rfc822. However, the email
headers that were saved on file in the %email_info_table were the headers of
the outer message.

This patch pulls the headers from the wrapped message to be saved in the
database. This mainly addresses the email References and In-Reply-To headers
for the email responses from the system.

Some emails providers (e.g gmail/google) won't deliver emails marked
bulk/autoreply to group email address.

This is required when validating a message which could be a string or an
object.

level.
Handle cases where thready body is sent in as a string

We're going to assume HTML of html thread is enabled - otherwise text is
assumed.

model.

This would in theory allow us to decide at the email level the content type
to accept.

Cleanup and make HTML safe by default
Strip empty lines in TEXT content

This will be helpful to keep track of whether a text is html or text and
provide a way to convert it exactly once.