Inline images other than small ones not appearing on Outlook Web Client

Question

I need to send Inline images in the body of my automatic reply mail , but I noticed that any image larger than 15Kb is failing to render in the Outlook Webclient. The images are url encoded in base64 and the body of the mail is sent as a HTML file.

        EmailMessage email = EmailMessage.bind(service, mail.getItemId());
        email.setIsRead(true);
        email.update(ConflictResolutionMode.AlwaysOverwrite);
        EmailMessage message = new EmailMessage(service);
        EmailAddress from = new EmailAddress(supportId);
        message.setSubject("Re: "+mail.getSubject());
        MessageBody hmtlBody = composeHtmlBody(BOX_NAME+"("+mail.getCategory()+")");
        message.setBody(hmtlBody);
        message.getToRecipients().add(mail.getFrom());
        message.setFrom(from);
        message.sendAndSaveCopy();

this is my html code

<p>Estimado Señor/Señora/Señorita,
    <br>
    <br>Reciba un cordial saludo, por favor su gentil ayuda comunicándose a nuestro Call Center 02-2999-999 o al 1700 800800 opción 2 para que el asesor realice la respectiva verificación y le brinden el soporte adecuado.
    <br>
    <br>
    <img alt="Logo" src="BASE64URL" height="350" width="450">
    <br>Saludos cordiales.
    <br>
    <br>Asesor Virtual

Tried with cid and baseurl64 , none of these help in rendering the image image_no_render