Testing RT5 and an email subject that contains an emoji, subject below
UTF8 working? 
← emoji
First question; Does RT5 support email when the subject contains an emoji?
Logs indicate no?
rt5 RT: [16565] DBD::mysql::st execute failed: Incorrect string value: '\xF0\x9F\xA4\xB7\xF0\x9F...' for
column `rt34`.`Tickets`.`Subject` at row 1 at /usr/share/perl5/DBIx/SearchBuilder/Handle.pm line 622.
System default character set to utf8
$ mysqladmin -u xxxxx -p var | grep -E 'character|collation' | tr -s ' '
Enter password:
| character_set_client | latin1 |
| character_set_connection | latin1 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | latin1 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
| collation_connection | latin1_swedish_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
| session_track_system_variables | autocommit,character_set_client,character_set_connection,character_set_results,time_zone |
Database default character set utf8mb4
> show create database rt34 ;
+----------+------------------------------------------------------------------+
| Database | Create Database |
+----------+------------------------------------------------------------------+
| rt34 | CREATE DATABASE `rt34` /*!40100 DEFAULT CHARACTER SET utf8mb4 */ |
+----------+------------------------------------------------------------------+
1 row in set (0.000 sec)
Table character set
> show full columns from Attachments where Field = "Subject" ;
+---------+--------------+--------------------+------+-----+---------+-------+---------------------------------+---------+
| Field | Type | Collation | Null | Key | Default | Extra | Privileges | Comment |
+---------+--------------+--------------------+------+-----+---------+-------+---------------------------------+---------+
| Subject | varchar(255) | utf8mb4_general_ci | YES | | NULL | | select,insert,update,references | |
+---------+--------------+--------------------+------+-----+---------+-------+---------------------------------+---------+
1 row in set (0.002 sec)