tonyparamo on "[Plugin: Contact Form 7] Failed to send msg redbox error on attach's larger than 750k"

November 18, 2013. WP 3.7.1, CF7 3.5.4
Get this error on attachments larger than 750k, anything smaller works just fine. I've tried the suggested WP-Mail-SMTP plugin, no luck. I've tried the default, changed to numbers, kb and mb. My host confirms limit is 20mb.

"Failed to send your message. Please try later or contact the administrator by another method." with red border.

denverartist.com/sample-page

Thanks.
Tony.

http://wordpress.org/plugins/contact-form-7/