This article details the maximum attachment size for PGP Web Messenger.
Email messages sent to Web Messenger users must be smaller than 50MB. Attachments to email replies created in PGP Universal Web Messenger are limited to 20MB per attachment. Also, users cannot send or receive any message that would put them over their message storage Quota. This limit is hard coded in the PGP Universal server.
PGP Universal Web Messenger mail gives recipients a way to securely read the message that was sent to them. This is available only if PGP Universal Server is in the mailstream.
Instead of sending the original message to the recipient, PGP Universal Web Messenger leaves the message on the PGP Universal Server and sends the recipient a notification message.
An optional method of sending attachments larger than 20MB would be to use the PGP Zip feature of PGP Desktop to encrypt the file(s) to the recipient's key and then email the PGP Zip attachment to the recipient.