Character Set Diagnosis

Current MySQL Connection Settings

Field	Type	Null	Key	Default	Extra
id	int	NO	PRI	NULL	auto_increment
eact_id	int	YES	UNI	NULL
activity_id	int	YES		NULL
emen_id	int	YES	MUL	NULL
entity_name	varchar(255)	YES	MUL	NULL
subject	varchar(255)	YES		NULL
from_address	varchar(255)	YES	MUL	NULL
to_address	text	YES		NULL
cc_address	text	YES		NULL
bcc_address	text	YES		NULL
body	text	YES		NULL
body_html	mediumtext	YES		NULL
date_created	datetime	YES	MUL	NULL
date_sent	datetime	YES		NULL
date_received	datetime	YES		NULL
direction	varchar(20)	YES		NULL
status	varchar(50)	YES		NULL
importance	varchar(20)	YES		NULL
message_id	varchar(255)	YES	MUL	NULL
thread_id	varchar(255)	YES	MUL	NULL
has_attachments	tinyint(1)	YES		0
attachment_count	int	YES		0
attachment_details	text	YES		NULL
tags	text	YES		NULL
creator_id	varchar(255)	YES		NULL
creator_name	varchar(255)	YES		NULL
assignee_id	varchar(50)	YES		NULL
assignee_name	varchar(255)	YES		NULL
raw_data	longtext	YES		NULL
sync_timestamp	timestamp	YES		CURRENT_TIMESTAMP	DEFAULT_GENERATED
last_updated	timestamp	YES		CURRENT_TIMESTAMP	DEFAULT_GENERATED on update CURRENT_TIMESTAMP

Name	Engine	Collation	Rows	Size
emails	InnoDB	utf8mb4_unicode_ci	38519	71942144

Field	Type	Collation	Null	Key	Default	Extra	Privileges	Comment
subject	varchar(255)	utf8mb4_unicode_ci	YES		NULL		select,insert,update,references	Email subject

For permanent fixes:

$this->db_connection->set_charset("utf8");

to:

$this->db_connection->set_charset("utf8mb4");

If your database connection settings still show "utf8" instead of "utf8mb4" after doing this, you may need to restart your web server.