For example, the DSN ``ses+smtp://ABC1234:abc+12/345@default`` should be

configured as ``ses+smtp://ABC1234:abc%2B12%2F345@default``

..caution::

If you want to use ``ses+smtp`` transport together with:doc:`Messenger</messenger>`

to:ref:`send messages in background<mailer-sending-messages-async>`,

you need to add ``ping_threshold`` parameter to your ``MAILER_DSN`` with

value lower than ``10``: ``ses+smtp://USERNAME:PASSWORD@default?ping_threshold=9``

..versionadded::5.4

The ``ping_threshold`` option for ``ses-smtp`` was introduced in Symfony 5.4.

..note::

When using SMTP, the default timeout for sending a message before throwing an

.. _mailer-sending-messages-async:

Sending Messages Async