iOS Client Not Showing Email Previews, Dovecot Issue?

[a...@globalchangemusic.org]

Greetings,

Just wondering if anybody would know why one of our users' iOS Mail app 
client doesn't show the email previews (the first few sentences of the 
email)?

We had migrated from an earlier (2.2.4) version of Dovecot to the latest 
version and once that was done, the user began to report this issue.  I 
don't know if it's a Dovecot issue or not, but can anyone point me in 
the right direction to begin to debug?

Thank you,
Asai