Description of problem:
Kmail gives error messages that it cannot append the mail. Looking in the logs shows that database issues are the problem. It is probably related to the mariadb update that was release.

From the Akonandi logs:
2023-02-17T15:58:59 [CRITICAL] org.kde.pim.akonadiserver: DATABASE ERROR:
2023-02-17T15:58:59 [CRITICAL] org.kde.pim.akonadiserver:   Error code: "1292"
2023-02-17T15:58:59 [CRITICAL] org.kde.pim.akonadiserver:   DB error:  "Incorrect datetime value: '2023-02-17T14:58:59Z' for column `akonadi`.`pimitemtable`.`atime` at row 1"
2023-02-17T15:58:59 [CRITICAL] org.kde.pim.akonadiserver:   Error text: "Incorrect datetime value: '2023-02-17T14:58:59Z' for column `akonadi`.`pimitemtable`.`atime` at row 1 QMYSQL: Unable to execute query"
2023-02-17T15:58:59 [CRITICAL] org.kde.pim.akonadiserver:   Values: QMap((":0", QVariant(QDateTime, QDateTime(2023-02-17 14:58:59.114 UTC Qt::UTC)))(":1", QVariant(qlonglong, 68266)))
2023-02-17T15:58:59 [CRITICAL] org.kde.pim.akonadiserver:   Query: "UPDATE PimItemTable SET atime = :0 WHERE ( ( PimItemTable.id = :1 ) )"
2023-02-17T15:58:59 [WARN ] org.kde.pim.akonadiserver: Unable to update item access time

Version-Release number of selected component (if applicable):
Kmail 20.12.0
Akonandi 20.12.0
Mariadb 10.5.13

How reproducible:
Have a working Kmail, update the software to these versions and try and recieve a new e-mail