Two plugins trying to declare the same function name.

as quick fix maybe you can rename the function of Elastic Email?

Hi,

I′d like to rename the functionof Elastic Email, but how.
Do you can tell me what do I have to change.

Here the code:

<?php
/*
Plugin Name: Elastic Email
Description: This plugin reconfigures the wp_mail() function to send email using HTTPS (via Elasticemail API) instead of SMTP and creates an options page that allows you to specify various options.
Version: 1.0
Author: esideout
Author URI: https://esideout.com
Plugin URI: https://esideout.com
*/

// Configuration options names:

define( 'EM_SETTINGS_GROUP', 'em_settings_group' );
define( 'EM_ENABLED', 'em_enabled' );
define( 'EM_USERNAME', '[email protected]' );
define( 'EM_APIKEY', '855da9fa-6c01-46b9-9c3f-29c35fd67ad1' );
define( 'EM_URL', 'em_url' );
define( 'EM_CHANNEL', 'em_channel' );

define( 'EM_PORT', 443 );
define( 'EM_HEADER_SEPARATOR', "\r\n" );
define( 'EM_TIMEOUT', 10 );
define( 'EM_READ_LENGTH', 1024 );
define( 'EM_EMAIL_SEPARATOR', ',' );

// Banner configuration

define( 'EM_BANNER', 'https://www.esideout.com/images/esideout-unix-technology-728x90-leaderboard.gif' );
define( 'EM_BANNER_LINK', 'https://www.esideout.com' );
define( 'EM_BANNER_ALT', 'Visit esideout.com' );

if ( is_admin() ) {
    add_action( 'admin_menu', 'em_admin_menu' );
}

function em_admin_menu() {
    add_options_page( 'Elastic Mail API', 'Elastic Email API', 'administrator', __FILE__, 'em_settings_page', '', __FILE__ );
}

function em_settings_page() {
    if ( !empty( $_POST ) ) {
        if ( isset( $_POST[ EM_ENABLED ] ) ) {
            update_option( EM_ENABLED, $_POST[ EM_ENABLED ] );
        } else {
            update_option ( EM_ENABLED, 0 );
        }
        if ( isset( $_POST[ EM_USERNAME ] ) ) {
            update_option( EM_USERNAME, $_POST[ EM_USERNAME ] );
        }
        if ( isset( $_POST[ EM_APIKEY ] ) ) {
            update_option( EM_APIKEY, $_POST[ EM_APIKEY ] );
        }
        if ( isset( $_POST[ EM_URL ] ) ) {
            update_option( EM_URL, $_POST[ EM_URL ] );
        }
        if ( isset( $_POST[ EM_CHANNEL ] ) ) {
            update_option( EM_CHANNEL, $_POST[ EM_CHANNEL ] );
        }

        $message = 'Options have been successfully saved.';
    }
?>
<div class="wrap">
    <h2>Elastic Mail Settings</h2>

    <?php if ( !empty( $message ) ): ?>
    <p><strong><?php echo $message ?></strong></p>
    <?php endif; ?>

    <form method="post" action="">

        <?php settings_fields( EM_SETTINGS_GROUP ); ?>
        <?php $enable_checked = get_option( EM_ENABLED ) ? ' checked="checked"' : ''; ?>

        <table class="form-table">
            <tr valign="top">
                <th scope="row">Enabled</th>
                <td><input type="checkbox" name="<?php echo EM_ENABLED ?>" value="1"<?php echo $enable_checked ?> /></td>
                <td><small>Enabled or disable Elastic mail API.</small></td>
            </tr>

            <tr valign="top">
                <th scope="row">API Username</th>
                <td><input type="text" name="<?php echo EM_USERNAME ?>" value="<?php echo get_option( EM_USERNAME ) ?>" size="32" /></td>
                <td><small>Elastic API username (can't be empty).</small></td>
            </tr>

            <tr valign="top">
                <th scope="row">API Key</th>
                <td><input type="text" name="<?php echo EM_APIKEY ?>" value="<?php echo get_option( EM_APIKEY ) ?>" size="32" /></td>
                <td><small>Elastic API Key (can't be empty).</small></td>
            </tr>

            <tr valign="top">
                <th scope="row">API URL</th>
                <td><input type="text" name="<?php echo EM_URL ?>" value="<?php echo get_option( EM_URL ) ?>" size="32" /></td>
                <td><small>Elastic API URL (can't be empty, default: ssl://api.elasticemail.com/mailer/send).</small></td>
            </tr>

            <tr valign="top">
                <th scope="row">API Channel</th>
                <td><input type="text" name="<?php echo EM_CHANNEL ?>" value="<?php echo get_option( EM_CHANNEL ) ?>" size="32" /></td>
                <td><small>Elastic API channel (can be empty).</small></td>
            </tr>

        </table>

        <p class="submit">
            <input type="submit" class="button-primary" value="<?php _e('Save Settings') ?>" />
        </p>

    </form>

    <p>
        <a href="<?php echo EM_BANNER_LINK ?>" title="<?php echo EM_BANNER_ALT ?>">
            <img src="<?php echo EM_BANNER ?>" alt="<?php echo EM_BANNER_ALT ?>" />
        </a>
    </p>

</div>
<?php
}

function em_enabled_configured() {
    $username = get_option( EM_USERNAME );
    $apikey = get_option( EM_APIKEY );
    return get_option( EM_ENABLED ) && !empty($username) && !empty($apikey);
}

function em_send( &$phpmailer, $to ) {
    $return = $errno = $errstr = NULL;

    $channel = get_option( EM_CHANNEL );

    if ( is_array( $to ) ) {
        $to = implode( EM_EMAIL_SEPARATOR, $to );
    }

    $data = 'username=' . urlencode( get_option( EM_USERNAME ) );
    $data .= '&api_key=' . urlencode( get_option( EM_APIKEY ) );
    $data .= '&from=' . urlencode( $phpmailer->From );
    $data .= '&from_name=' . urlencode( $phpmailer->FromName );
    $data .= '&to=' . urlencode( $to );
    $data .= '&subject=' . urlencode( $phpmailer->Subject );

    if ( $phpmailer->ContentType == 'text/html' ) {
         $data .= '&body_html=' . urlencode( $phpmailer->Body );
         $data .= '&body_text=' . urlencode( strip_tags( $phpmailer->Body ) );
    } else {
         $data .= '&body_text=' . urlencode( $phpmailer->Body );
    }

    if ( !empty( $channel ) ) {
        $data .= '&channel=' . urlencode( $channel );
    }

    $url = get_option( EM_URL );
    $url_data = parse_url( $url );

    $hostname = $url_data['scheme'] . '://' . $url_data['host'];

    $headers = 'POST ' . $url_data['path'] . ' HTTP/1.0' . EM_HEADER_SEPARATOR;
    $headers .= 'Content-Type: application/x-www-form-urlencoded' . EM_HEADER_SEPARATOR;
    $headers .= 'Content-Length: ' . strlen($data) . EM_HEADER_SEPARATOR . EM_HEADER_SEPARATOR;

    $fp = fsockopen( $hostname, EM_PORT, $errno, $errstr, EM_TIMEOUT);

    if ( !$fp ) {
        return FALSE;
    } else {
        fputs( $fp, $headers . $data );

        while ( !feof( $fp ) ) {
            $return .= fread ( $fp, EM_READ_LENGTH );
        }

        fclose( $fp );
    }

    return ( substr_count( $return, '200 OK' ) > 0 );
}

if ( em_enabled_configured() && !function_exists('wp_mail') ) {

/**
 * This was wp_mail() funtion from WordPress 3.2.1
 *
 * @param string|array $to Array or comma-separated list of email addresses to send message.
 * @param string $subject Email subject
 * @param string $message Message contents
 * @param string|array $headers Optional. Additional headers.
 * @param string|array $attachments Optional. Files to attach.
 * @return bool Whether the email contents were sent successfully.
 */
function wp_mail( $to, $subject, $message, $headers = '', $attachments = array() ) {
    // Compact the input, apply the filters, and extract them back out
    extract( apply_filters( 'wp_mail', compact( 'to', 'subject', 'message', 'headers', 'attachments' ) ) );

    // Doesn't support attachments
    if ( !empty($attachments) ) {
        return FALSE;
    }

    if ( !is_array($attachments) )
        $attachments = explode( "\n", str_replace( "\r\n", "\n", $attachments ) );

    global $phpmailer;

    // (Re)create it, if it's gone missing
    if ( !is_object( $phpmailer ) || !is_a( $phpmailer, 'PHPMailer' ) ) {
        require_once ABSPATH . WPINC . '/class-phpmailer.php';
        require_once ABSPATH . WPINC . '/class-smtp.php';
        $phpmailer = new PHPMailer( true );
    }

    // Headers
    if ( empty( $headers ) ) {
        $headers = array();
    } else {
        if ( !is_array( $headers ) ) {
            // Explode the headers out, so this function can take both
            // string headers and an array of headers.
            $tempheaders = explode( "\n", str_replace( "\r\n", "\n", $headers ) );
        } else {
            $tempheaders = $headers;
        }
        $headers = array();
        $cc = array();
        $bcc = array();

        // If it's actually got contents
        if ( !empty( $tempheaders ) ) {
            // Iterate through the raw headers
            foreach ( (array) $tempheaders as $header ) {
                if ( strpos($header, ':') === false ) {
                    if ( false !== stripos( $header, 'boundary=' ) ) {
                        $parts = preg_split('/boundary=/i', trim( $header ) );
                        $boundary = trim( str_replace( array( "'", '"' ), '', $parts[1] ) );
                    }
                    continue;
                }
                // Explode them out
                list( $name, $content ) = explode( ':', trim( $header ), 2 );

                // Cleanup crew
                $name    = trim( $name    );
                $content = trim( $content );

                switch ( strtolower( $name ) ) {
                    // Mainly for legacy -- process a From: header if it's there
                    case 'from':
                        if ( strpos($content, '<' ) !== false ) {
                            // So... making my life hard again?
                            $from_name = substr( $content, 0, strpos( $content, '<' ) - 1 );
                            $from_name = str_replace( '"', '', $from_name );
                            $from_name = trim( $from_name );

                            $from_email = substr( $content, strpos( $content, '<' ) + 1 );
                            $from_email = str_replace( '>', '', $from_email );
                            $from_email = trim( $from_email );
                        } else {
                            $from_email = trim( $content );
                        }
                        break;
                    case 'content-type':
                        if ( strpos( $content, ';' ) !== false ) {
                            list( $type, $charset ) = explode( ';', $content );
                            $content_type = trim( $type );
                            if ( false !== stripos( $charset, 'charset=' ) ) {
                                $charset = trim( str_replace( array( 'charset=', '"' ), '', $charset ) );
                            } elseif ( false !== stripos( $charset, 'boundary=' ) ) {
                                $boundary = trim( str_replace( array( 'BOUNDARY=', 'boundary=', '"' ), '', $charset ) );
                                $charset = '';
                            }
                        } else {
                            $content_type = trim( $content );
                        }
                        break;
                    case 'cc':
                        $cc = array_merge( (array) $cc, explode( ',', $content ) );
                        break;
                    case 'bcc':
                        $bcc = array_merge( (array) $bcc, explode( ',', $content ) );
                        break;
                    default:
                        // Add it to our grand headers array
                        $headers[trim( $name )] = trim( $content );
                        break;
                }
            }
        }
    }

    // Empty out the values that may be set
    $phpmailer->ClearAddresses();
    $phpmailer->ClearAllRecipients();
    $phpmailer->ClearAttachments();
    $phpmailer->ClearBCCs();
    $phpmailer->ClearCCs();
    $phpmailer->ClearCustomHeaders();
    $phpmailer->ClearReplyTos();

    // From email and name
    // If we don't have a name from the input headers
    if ( !isset( $from_name ) )
        $from_name = 'WordPress';

    /* If we don't have an email from the input headers default to wordpress@$sitename
     * Some hosts will block outgoing mail from this address if it doesn't exist but
     * there's no easy alternative. Defaulting to admin_email might appear to be another
     * option but some hosts may refuse to relay mail from an unknown domain. See
     * https://trac.www.ads-software.com/ticket/5007.
     */

    if ( !isset( $from_email ) ) {
        // Get the site domain and get rid of www.
        $sitename = strtolower( $_SERVER['SERVER_NAME'] );
        if ( substr( $sitename, 0, 4 ) == 'www.' ) {
            $sitename = substr( $sitename, 4 );
        }

        $from_email = 'wordpress@' . $sitename;
    }

    // Plugin authors can override the potentially troublesome default
    $phpmailer->From     = apply_filters( 'wp_mail_from'     , $from_email );
    $phpmailer->FromName = apply_filters( 'wp_mail_from_name', $from_name  );

    // Set destination addresses
    if ( !is_array( $to ) )
        $to = explode( ',', $to );

    foreach ( (array) $to as $recipient ) {
        try {
            // Break $recipient into name and address parts if in the format "Foo <[email protected]>"
            $recipient_name = '';
            if( preg_match( '/(.+)\s?<(.+)>/', $recipient, $matches ) ) {
                if ( count( $matches ) == 3 ) {
                    $recipient_name = $matches[1];
                    $recipient = $matches[2];
                }
            }
            $phpmailer->AddAddress( trim( $recipient ), $recipient_name);
        } catch ( phpmailerException $e ) {
            continue;
        }
    }

    // Set mail's subject and body
    $phpmailer->Subject = $subject;
    $phpmailer->Body    = $message;

    // Add any CC and BCC recipients
    if ( !empty( $cc ) ) {
        foreach ( (array) $cc as $recipient ) {
            try {
                // Break $recipient into name and address parts if in the format "Foo <[email protected]>"
                $recipient_name = '';
                if( preg_match( '/(.+)\s?<(.+)>/', $recipient, $matches ) ) {
                    if ( count( $matches ) == 3 ) {
                        $recipient_name = $matches[1];
                        $recipient = $matches[2];
                    }
                }
                $phpmailer->AddCc( trim($recipient), $recipient_name );
            } catch ( phpmailerException $e ) {
                continue;
            }
        }
    }

    if ( !empty( $bcc ) ) {
        foreach ( (array) $bcc as $recipient) {
            try {
                // Break $recipient into name and address parts if in the format "Foo <[email protected]>"
                $recipient_name = '';
                if( preg_match( '/(.+)\s?<(.+)>/', $recipient, $matches ) ) {
                    if ( count( $matches ) == 3 ) {
                        $recipient_name = $matches[1];
                        $recipient = $matches[2];
                    }
                }
                $phpmailer->AddBcc( trim($recipient), $recipient_name );
            } catch ( phpmailerException $e ) {
                continue;
            }
        }
    }

    // Set to use PHP's mail()
    $phpmailer->IsMail();

    // Set Content-Type and charset
    // If we don't have a content-type from the input headers
    if ( !isset( $content_type ) )
        $content_type = 'text/plain';

    $content_type = apply_filters( 'wp_mail_content_type', $content_type );

    $phpmailer->ContentType = $content_type;

    // Set whether it's plaintext, depending on $content_type
    if ( 'text/html' == $content_type )
        $phpmailer->IsHTML( true );

    // If we don't have a charset from the input headers
    if ( !isset( $charset ) )
        $charset = get_bloginfo( 'charset' );

    // Set the content-type and charset
    $phpmailer->CharSet = apply_filters( 'wp_mail_charset', $charset );

    // Set custom headers
    if ( !empty( $headers ) ) {
        foreach( (array) $headers as $name => $content ) {
            $phpmailer->AddCustomHeader( sprintf( '%1$s: %2$s', $name, $content ) );
        }

        if ( false !== stripos( $content_type, 'multipart' ) && ! empty($boundary) )
            $phpmailer->AddCustomHeader( sprintf( "Content-Type: %s;\n\t boundary=\"%s\"", $content_type, $boundary ) );
    }

    if ( !empty( $attachments ) ) {
        foreach ( $attachments as $attachment ) {
            try {
                $phpmailer->AddAttachment($attachment);
            } catch ( phpmailerException $e ) {
                continue;
            }
        }
    }

    do_action_ref_array( 'phpmailer_init', array( &$phpmailer ) );

    // Send!
    try {
        //$phpmailer->Send();
        return em_send( $phpmailer, $to );
    } catch ( phpmailerException $e ) {
        return false;
    }

}
}

Thank You!

do a search/replace e.g. on notepad or similar

e.g. search em_admin_menu

replace em_x_admin_menu