Is you Horde email failing due to file size attachments? Check the php.ini file in horde:
[root@server ~]# grep upload_max_filesize /etc/psa-webmail/horde/horde/php.ini upload_max_filesize = 5M
Now edit the file:
[root@server ~]# nano /etc/psa-webmail/horde/horde/php.ini
upload_max_filesize = 5M
Change to required value
upload_max_filesize = 128M
Save and exit and restart horde
SERVICE HORDE RESTART
Now check the php config file – php.ini for max_uploads and max_post
grep max_file_uploads /etc/php.ini
max_file_uploads = 99999