function calculate_references - calculate correct References string Adds the current message ID, and makes sure it doesn't grow forever, to that extent it drops message-ID's in a smart way until the string length is under the recommended value of 1000 ("References: <986>\r\n").

It always keeps the first and the last three ID's.

• return: concatenated and trimmed References string

• Rfc822Header $hdr: message header to calculate from

Fold header lines per RFC 2822/2.2.3 and RFC 822/3.1.1

Herein "soft" folding/wrapping (with whitespace tokens) is what we refer to as the preferred method of wrapping - that which we'd like to do within the $soft_wrap limit, but if not possible, we will try to do as soon as possible after $soft_wrap up to the $hard_wrap limit. Encoded words don't need to be detected in this phase, since they cannot contain spaces.

"Hard" folding/wrapping (with "hard" tokens) is what we refer to as less ideal wrapping that will be done to keep within the $hard_wrap limit. This adds other syntactical breaking elements such as commas and encoded words.

• return: The folded header content, with a trailing CRLF.

• string $header: The header content being folded
• integer $soft_wrap: The desirable maximum line length (OPTIONAL; default is 78, per RFC)
• string $indent: Wrapped lines will already have whitespace following the CRLF wrap, but you can add more indentation (or whatever) with this. The use of this parameter is DISCOURAGED, since it can corrupt the redisplay (unfolding) of headers whose content is space- sensitive, like subjects, etc. (OPTIONAL; default is an empty string)
• string $hard_wrap: The absolute maximum line length (OPTIONAL; default is 998, per RFC)

function initStream - reserved for extended functionality

This function is not yet implemented. Reserved for extended functionality. UPDATE: It is implemented in Deliver_SMTP and Deliver_SendMail classes, but it remains unimplemented in this base class (and thus not in Deliver_IMAP or other child classes that don't define it)

NOTE: some parameters are specific to the child class that is implementing this method

• return: file handle resource to SMTP stream

• Message $message: Message object
• string $domain
• integer $length
• string $host: host name or IP to connect to
• integer $port
• string $user: username to log into the SMTP server with
• string $pass: password to log into the SMTP server with
• boolean $authpop: whether or not to use POP-before-SMTP authorization
• string $pop_host: host name or IP to connect to for POP-before-SMTP authorization
• array $stream_options: Stream context options, see config_local.example.php for more details (OPTIONAL)

• Deliver_SMTP::initStream()
• Deliver_SendMail::initStream() : function initStream

function mail - send the message parts to the SMTP stream

• return: The number of bytes written (or that would have been written) to the output stream.

• Message $message: Message object to send NOTE that this is passed by reference and will be modified upon return with updated fields such as Message ID, References, In-Reply-To and Date headers.
• resource $stream: Handle to the outgoing stream (when FALSE, nothing will be written to the stream; this can be used to determine the actual number of bytes that will be written to the stream)
• string $reply_id: Identifies message being replied to (OPTIONAL; caller should ONLY specify a value for this when the message being sent is a reply)
• string $reply_ent_id: Identifies message being replied to in the case it was an embedded/attached message inside another (OPTIONAL; caller should ONLY specify a value for this when the message being sent is a reply)
• resource $imap_stream: If there is an open IMAP stream in the caller's context, it should be passed in here. This is OPTIONAL, as one will be created if not given, but as some IMAP servers may baulk at opening more than one connection at a time, the caller should always abide if possible. Currently, this stream is only used when $reply_id is also non-zero, but that is subject to change.
• mixed $extra: Any implementation-specific variables can be passed in here and used in an overloaded version of this method if needed.
• &$message

function prepareMIME_Header - creates the mime header

• return: properly formatted mime header

• Message $message: Message object to act on
• string $boundary: mime boundary from fn MimeBoundary

function preWriteToStream - reserved for extended functionality

This function is not yet implemented. Reserved for extended functionality.

• string &$s: string to operate on

• Deliver_SMTP::preWriteToStream()

function strip_crlf - strip linefeeds and newlines from a string

The SMTP format only allows CRLF as line terminators. This function strips all line terminators from the string.

• string &$s: string to clean linefeeds on

function writeBody - generate and write the mime boundaries around each part to the stream

Recursively formats and writes the MIME boundaries of the $message to the output stream.

• Message $message: Message object to transform
• resource $stream: SMTP output stream (when FALSE, nothing will be written to the stream; this can be used to determine the actual number of bytes that will be written to the stream)
• integer &$length_raw: raw length of the message (part) as returned by mail fn
• string $boundary: custom boundary to call, usually for subparts

function writeToStream - write data to the SMTP stream

• resource $stream: SMTP output stream
• string $data: string with data to send to the SMTP stream