If you want to ensure that Spark is connecting securely using TLS, you may need to change the Advanced settings for your email account. According to Spark’s own documentation, there is no way to change these settings, and they advise you to remove and re-create the account.
Spark’s documentation states that “Removing your account from Spark won’t delete your emails as they are saved on the email server of your provider.”. Normally we’d advise you to take a backup of the email data before proceeding, however Spark’s documentation on this states that they do not have any backup/export features available. The reason behind this, is because Spark will only connect to our email server via IMAP, which means that emails are never saved locally because they’re all stored on the email server.
In theory, this would mean that it’s fine to remove the account and re-add it by following these steps for Mac and these steps for IPhone. If you want to confirm that your emails all exist on the server before proceeding, you can log in to the webmail interface to verify that all of your emails are there.