Previously opened on [Civicore](https://lab.civicrm.org/dev/core/-/issues/4050) Overview ---------------------------------------- When performing an offline Event Registration, you cannot disable "Send Confirmation and Receipt". The POST handler ```civicrm/contact/view/participant``` sends out emails irrespective of the disabled checkbox on the UI and the disabled default event page configuration. https://chat.civicrm.org/civicrm/pl/4uy3mp5c3jbtjdx96fif6nk4ie _If you have already posted on https://civicrm.stackexchange.com or https://chat.civicrm.org, please include the link to that conversation._ Reproduction steps ---------------------------------------- 1. Open a Contact 1. Click on **Actions-> Register for Event**. 1. After any Event, Disable **☑️ Send Confirmation and Receipt** and **Save**. 1. Got a success of **"Event registration for Test Email has been added. A confirmation email has been sent to"**. (No email should have been sent) Current behaviour ---------------------------------------- _What happens currently. Please provide error messages, screenshots or gifs ([LICEcap](http://www.cockos.com/licecap/), [SilentCast](https://github.com/colinkeenan/silentcast)) where appropriate._ Currently Sends this payload with a disabled send notification and disabled Payment box ``` entryURL: https://example.website/wp-admin/admin.php?page=CiviCRM&amp;q=civicrm%2Fcontact%2Fview%2Fparticipant&amp;page=CiviCRM&amp;reset=1&amp;action=add&amp;cid=497&amp;context=participant _qf_default: Participant:upload MAX_FILE_SIZE: 83886080 _qf_Participant_upload: 1 contact_id: 497 event_id: 15 campaign_id: 8 role_id[]: 1 register_date: 2022-12-27 13:23:00 status_id: 1 source: hidden_feeblock: 1 hidden_eventFullMsg: priceSetId: 10 price_16: price_13: price_11: financial_type_id: 4 total_amount: 0 receive_date: 2022-12-27 13:23:00 trxn_id: contribution_status_id: 1 payment_instrument_id: 4 check_number: from_email_address: 185 receipt_text: note: hidden_custom: 1 hidden_custom_group_count[]: 1 custom_21_-1: custom_18_-1: 0 custom_19_-1: 0 custom_20_-1: 0 custom_22_-1: hidden_custom: 1 hidden_custom_group_count[]: 1 hidden_custom: 1 hidden_custom_group_count[]: 1 hidden_custom: 1 hidden_custom_group_count[]: 1 ``` I injected a null value into the options to select from the drop down which changed the parameter of ```from_email_address: 185``` to ```from_email_address: ``` Unfortunately, that is not how the post handler determines if to send a message because i got this error:  So it still tried to send with the unset email address. Expected behaviour ---------------------------------------- _What should happen._ No email is sent. Environment information ---------------------------------------- <!-- Some of the items below may not be relevant for every bug - if in doubt please include more information than you think is neccessary. --> * __Browser:__ _Edge 108.0.1462.54_ * __CiviCRM:__ _5.56.0, 5.55.3_ * __PHP:__ _7.4?_ * __CMS:__ _Wordpress 6.1.1_ * __Database:__ _Maria DB_ * __Web Server:__ _Apache 2_ * __Extension:__ _CiviMobileAPI 6.1.1_ Comments ---------------------------------------- I'm not skilled in reading how php handles calls and everything, so i can't find the handler that this post query relates to. Any pointers would help!