I didn't wanted to create 2 gitst, so the Address class is at the bottom

ImapHeaderWrapper.php

<?php

/**
 * Class EmailHeader
 *
 * I'm sick of darn stdClasses, so I made this
 * it doesn't cover every possible properties
 *
 * @link http://php.net/manual/en/function.imap-headerinfo.php
 */
class EmailHeader
{
    const FLAG_NOT             = ' ';
    const FLAG_RECENT_SEEN     = 'R';
    const FLAG_RECENT_UNSEEN   = 'N';
    const FLAG_UNSEEN          = 'U';
    const FLAG_FLAGGED         = 'F';
    const FLAG_ANSWERED        = 'A';
    const FLAG_DELETED         = 'D';
    const FLAG_DRAFT           = 'X';

    #region Addresses

    /**
     * full to: line, up to 1024 characters
     *
     * @var null|string {1024}
     */
    protected $toAddress = null;

    /**
     * @var Address[]
     */
    protected $to = [];

    /**
     * full from: line, up to 1024 characters
     *
     * @var null|string
     */
    protected $fromAddress = null;

    /**
     * @var Address[]
     */
    protected $from = [];

    /**
     * full cc: line, up to 1024 characters
     *
     * @var null|string
     */
    protected $ccAddress = null;

    /**
     * @var Address[]
     */
    protected $cc = [];


    /**
     * full cc: line, up to 1024 characters
     *
     * @var null|string
     */
    protected $bccAddress = null;

    /**
     * @var Address[]
     */
    protected $bcc = [];

    /**
     * full to: line, up to 1024 characters
     *
     * @var null|string {1024}
     */
    protected $replyToAddress = null;

    /**
     * @var Address[]
     */
    protected $replyTo = [];

    /**
     * full to: line, up to 1024 characters
     *
     * @var null|string {1024}
     */
    protected $senderAddress = null;

    /**
     * @var Address[]
     */
    protected $sender = [];

    /**
     * full to: line, up to 1024 characters
     *
     * @var null|string {1024}
     */
    protected $returnPathAddress = null;

    /**
     * @var Address[]
     */
    protected $returnPath = [];

    #endregion

    /** @var \DateTime */
    protected $date;

    /** @var int unix time */
    protected $uDate;

    /** @var string */
    protected $subject;

    /** @var string */
    protected $messageId;

    /** @var null|string  */
    protected $inReplyTo = null;

    /** @var null|string */
    protected $followUpTo = null;

    #region FLAGS

    /**
     * R if recent and seen, N if recent and not seen, ' ' if not recent
     *
     * @var string
     */
    protected $recent = self::FLAG_NOT;

    /**
     * U if not seen AND not recent, ' ' if seen OR not seen and recent
     *
     * @var string
     */
    protected $unseen = self::FLAG_NOT;

    /**
     * F if flagged, ' ' if not flagged
     *
     * @var string
     */
    protected $flagged = self::FLAG_NOT;

    /**
     * A if answered, ' ' if unanswered
     *
     * @var string
     */
    protected $answered = self::FLAG_NOT;

    /**
     * D if deleted, ' ' if not deleted
     *
     * @var string
     */
    protected $deleted = self::FLAG_NOT;

    /**
     * X if draft, ' ' if not draft
     *
     * @var string
     */
    protected $draft = self::FLAG_NOT;

    #endregion

    /** @var int */
    protected $msgNo = 0;

    /** @var int */
    protected $size = 0;

    /**
     * EmailHeader constructor.
     *
     * @param \stdClass $headerInfo            the data returned from `imap_headerinfo`
     * @param bool      $skippInvalidAddresses if true, invalid addresses won't be processed
     */
    public function __construct(\stdClass $headerInfo, $skippInvalidAddresses = false)
    {
        #region addresses
        if ( isset($headerInfo->toaddress) ) {
            $this->toAddress = $headerInfo->toaddress;
        }

        if ( isset($headerInfo->to) && is_array($headerInfo->to) ) {
            $this->to = $this->createAddressArray($headerInfo->to, $skippInvalidAddresses);
        }

        if ( isset($headerInfo->fromaddress) ) {
            $this->fromAddress = $headerInfo->fromaddress;
        }

        if ( isset($headerInfo->from) && is_array($headerInfo->from) ) {
            $this->from = $this->createAddressArray($headerInfo->from, $skippInvalidAddresses);
        }

        if ( isset($headerInfo->ccaddress) ) {
            $this->ccAddress = $headerInfo->ccaddress;
        }

        if ( isset($headerInfo->cc) && is_array($headerInfo->cc) ) {
            $this->cc = $this->createAddressArray($headerInfo->cc, $skippInvalidAddresses);
        }

        if ( isset($headerInfo->bccaddress) ) {
            $this->bccAddress = $headerInfo->bccaddress;
        }

        if ( isset($headerInfo->bcc) && is_array($headerInfo->bcc) ) {
            $this->bcc = $this->createAddressArray($headerInfo->bcc, $skippInvalidAddresses);
        }

        if ( isset($headerInfo->reply_toaddress) ) {
            $this->replyToAddress = $headerInfo->reply_toaddress;
        }

        if ( isset($headerInfo->reply_to) && is_array($headerInfo->reply_to) ) {
            $this->replyTo = $this->createAddressArray($headerInfo->reply_to, $skippInvalidAddresses);
        }

        if ( isset($headerInfo->senderaddress) ) {
            $this->senderAddress = $headerInfo->senderaddress;
        }

        if ( isset($headerInfo->sender) && is_array($headerInfo->sender) ) {
            $this->sender = $this->createAddressArray($headerInfo->sender, $skippInvalidAddresses);
        }

        if ( isset($headerInfo->return_pathaddress) ) {
            $this->returnPathAddress = $headerInfo->return_pathaddress;
        }

        if ( isset($headerInfo->return_path) && is_array($headerInfo->return_path) ) {
            $this->returnPath = $this->createAddressArray($headerInfo->return_path, $skippInvalidAddresses);
        }
        #endregion

        if ( isset($headerInfo->date) || isset($headerInfo->Date) ) {
            $this->date = isset($headerInfo->date) ?
                new \DateTime($headerInfo->date) :
                new \DateTime($headerInfo->Date);
        }

        if ( isset($headerInfo->udate) ) {
            $this->uDate = $headerInfo->udate;

            if ( null === $this->date ) {
                $this->date = \DateTime::createFromFormat('U', $headerInfo->udate);
            }
        }

        if ( isset($headerInfo->subject) || isset($headerInfo->Subject) ) {
            $this->subject = isset($headerInfo->subject) ?
                $headerInfo->subject :
                $headerInfo->Subject;
        }

        if ( isset($headerInfo->in_reply_to) ) {
            $this->inReplyTo = $headerInfo->in_reply_to;
        }

        if ( isset($headerInfo->message_id) ) {
            $this->messageId = $headerInfo->message_id;
        }

        if ( isset($headerInfo->followup_to) ) {
            $this->followUpTo = $headerInfo->followup_to;
        }

        if ( isset($headerInfo->Recent) ) {
            $this->recent = $headerInfo->Recent;
        }

        if ( isset($headerInfo->Unseen) ) {
            $this->unseen = $headerInfo->Unseen;
        }

        if ( isset($headerInfo->Flagged) ) {
            $this->flagged = $headerInfo->Flagged;
        }

        if ( isset($headerInfo->Answered) ) {
            $this->answered = $headerInfo->Answered;
        }

        if ( isset($headerInfo->Deleted) ) {
            $this->deleted = $headerInfo->Deleted;
        }

        if ( isset($headerInfo->Draft) ) {
            $this->draft = $headerInfo->Draft;
        }

        if ( isset($headerInfo->Msgno) ) {
            $this->msgNo = $headerInfo->Msgno;
        }

        if ( isset($headerInfo->Size) ) {
            $this->size = $headerInfo->Size;
        }
    }
    
    /**
     * @return bool
     */
    public function isValid()
    {
        return $this->messageId !== null;
    }

    /**
     * @param \stdClass[] $addresses
     * @param bool        $filterInvalid if true, invalid addresses are not added
     *
     * @return Address[]
     */
    protected function createAddressArray(array $addresses, $filterInvalid = false)
    {
        $addressArray = [];

        foreach($addresses as $addressData) {
            $properObj = new Address($addressData);

            if ( !$filterInvalid || $properObj->isValid() ) {
                $addressArray[] = $properObj;
            }
        }

        return $addressArray;
    }

    #region simple properties

    /**
     * @return null|string
     */
    public function getToAddress()
    {
        return $this->toAddress;
    }

    /**
     * @return null|string
     */
    public function getFromAddress()
    {
        return $this->fromAddress;
    }

    /**
     * @return null|string
     */
    public function getCcAddress()
    {
        return $this->ccAddress;
    }

    /**
     * @return null|string
     */
    public function getBccAddress()
    {
        return $this->bccAddress;
    }

    /**
     * @return null|string
     */
    public function getReplyToAddress()
    {
        return $this->replyToAddress;
    }

    /**
     * @return null|string
     */
    public function getSenderAddress()
    {
        return $this->senderAddress;
    }

    /**
     * @return null|string
     */
    public function getReturnPathAddress()
    {
        return $this->returnPathAddress;
    }

    /**
     * @return \DateTime
     */
    public function getDate()
    {
        return $this->date;
    }

    /**
     * @return int
     */
    public function getUDate()
    {
        return $this->uDate;
    }

    /**
     * @return string
     */
    public function getSubject()
    {
        return $this->subject;
    }

    /**
     * @return string
     */
    public function getMessageId()
    {
        return $this->messageId;
    }

    /**
     * @return null|string
     */
    public function getInReplyTo()
    {
        return $this->inReplyTo;
    }

    /**
     * @return null|string
     */
    public function getFollowUpTo()
    {
        return $this->followUpTo;
    }

    /**
     * @return int
     */
    public function getMsgNo()
    {
        return $this->msgNo;
    }

    /**
     * @return int
     */
    public function getSize()
    {
        return $this->size;
    }

    #endregion

    #region Address-Getters

    /**
     * @return Address[]
     */
    public function getTo()
    {
        return $this->to;
    }

    /**
     * @return Address[]
     */
    public function getFrom()
    {
        return $this->from;
    }

    /**
     * @return Address[]
     */
    public function getCc()
    {
        return $this->cc;
    }

    /**
     * @return Address[]
     */
    public function getBcc()
    {
        return $this->bcc;
    }

    /**
     * @return Address[]
     */
    public function getReplyTo()
    {
        return $this->replyTo;
    }

    /**
     * @return Address[]
     */
    public function getSender()
    {
        return $this->sender;
    }

    /**
     * @return Address[]
     */
    public function getReturnPath()
    {
        return $this->returnPath;
    }

    #endregion

    #region FLAG-GETTERS

    /**
     * @return bool
     */
    public function isRecent()
    {
        return in_array($this->recent, [self::FLAG_RECENT_SEEN, self::FLAG_RECENT_UNSEEN]);
    }

    /**
     * @return bool
     */
    public function isUnseen()
    {
        return $this->unseen === self::FLAG_UNSEEN;
    }

    /**
     * @return bool
     */
    public function isFlagged()
    {
        return $this->flagged === self::FLAG_FLAGGED;
    }

    /**
     * @return bool
     */
    public function isAnswered()
    {
        return $this->answered === self::FLAG_ANSWERED;
    }

    /**
     * @return bool
     */
    public function isDeleted()
    {
        return $this->deleted === self::FLAG_DELETED;
    }

    /**
     * @return bool
     */
    public function isDraft()
    {
        return $this->draft === self::FLAG_DRAFT;
    }

    #endregion
}

final class Address
{
    /** @var string|null */
    private $personal = null;
    /** @var string|null */
    private $adl      = null;
    /** @var string|null */
    private $mailbox  = null;
    /** @var string|null */
    private $host     = null;

    /**
     * Address constructor.
     *
     * @param \stdClass $addressData
     */
    public function __construct(\stdClass $addressData)
    {
        if ( isset($addressData->personal) )
        $this->personal = $addressData->personal;

        if ( isset($addressData->adl) )
        $this->adl = $addressData->adl;

        if ( isset($addressData->mailbox) )
        $this->mailbox = $addressData->mailbox;

        if ( isset($addressData->host) )
        $this->host  = $addressData->host;
    }

    /**
     * @return bool
     */
    public function isValid()
    {
        return $this->mailbox !== null && $this->host !== null;
    }

    /**
     * @return string
     */
    public function getName()
    {
        return $this->personal;
    }

    /**
     * @return string
     */
    public function getAddress()
    {
        return $this->mailbox . '@' . $this->host;
    }
}