Missing Input Parameters Error
This sounds like an issue a customer of ours encountered. In the end they resolved it at the device level.
From our issue tracker notes on the subject:

The issue is to do with character encodings. CiviCRM emails are sent with the following headers:

Content-Transfer-Encoding: 8bit
Content-Type: text/html; charset=utf-8


Whereas it appears Exchange is re-encoding these as 'quoted-printable' when serving them to the iOS device:

Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: quoted-printable

Here was their final feedback to us

&quot;You were right about this being something to do with legacy mailservers, etc. Sort of. I sorted out how to replicate this behavior on ANY iOS device. Simply create a new mail account on your iOS device using the &quot;Exchange&quot; option as outlined here: http://www.macobserver.com/tmo/article/how-to-set-up-gmail-on-ios-using-exchange-activesync
Although he isn't here today to ask, I believe our ED has his email setup this way on both his iPhone and iPad, and this is causing the issue. I will check in with the member who is experiencing the same issue and see if they are on an Exchange server or a Google mailserver set up in a similar manner.
I'm setting this to resolved, and we'll work internally to get all our people on the correct iOS settings.
Thanks much for your help!&quot;