iOS Email Requirements
Here is an requirement the iOS devices have for email.
iOS Pre-Header Character Count:
We have detected that you do not have enough characters before your closing </head> tag in order for the email to completely load in an iOS device. There must be at least 1,109 characters before the closing </head> or there will be a “Partial Loaded” message displayed to the end user. If this is not fixed you will get a partial result for supported iOS devices.