VZW IPv6 routing issues?

[Drew Linsalata <drew.linsalata () gmail com>]

Shot in the dark here, but we're starting to see complaints from a few VZW
customers that can no longer access mail services we're providing on the
usual IMAP and POP ports (secure or otherwise).  It only seems to be
happening for users that are getting IPv6 addresses for cellular data.  Web
traffic isn't an issue, just mail.

Has anyone else seen this?