Unable to send SMTP message with Exchange

Hello,
I installed Vaultwarden 1.26 on a Synology (DSM 7.1.1).
I’m able to send mails with the smtp server of my provider.
But with my internal Exchange 2013 I get this error :
Can anyone tell me where and what to look for?

022-11-24T10:22:42.573731675Z	stdout	[2022-11-24 10:22:42.571][vaultwarden::mail][ERROR] SMTP Connection error: Connection error: unexpected EOF
2022-11-24T10:22:42.573672776Z	stdout	}
2022-11-24T10:22:42.573588403Z	stdout	    },
2022-11-24T10:22:42.572964154Z	stdout	        ),
2022-11-24T10:22:42.572876523Z	stdout	            },
2022-11-24T10:22:42.572770114Z	stdout	                error: "ok",
2022-11-24T10:22:42.572692036Z	stdout	                code: 0,
2022-11-24T10:22:42.572614640Z	stdout	            X509VerifyResult {
2022-11-24T10:22:42.572529635Z	stdout	            },
2022-11-24T10:22:42.572448490Z	stdout	                cause: None,
2022-11-24T10:22:42.572373140Z	stdout	                ),
2022-11-24T10:22:42.572296386Z	stdout	                    5,
2022-11-24T10:22:42.572215671Z	stdout	                code: ErrorCode(
2022-11-24T10:22:42.572139128Z	stdout	            Error {
2022-11-24T10:22:42.572058564Z	stdout	        source: Ssl(
2022-11-24T10:22:42.571978903Z	stdout	        kind: Connection,
2022-11-24T10:22:42.571892354Z	stdout	    source: lettre::transport::smtp::Error {
2022-11-24T10:22:42.571773032Z	stdout	    kind: Connection,
2022-11-24T10:22:42.571580665Z	stdout	[2022-11-24 10:22:42.571][vaultwarden::mail][DEBUG] SMTP lettre::transport::smtp::Error {
2022-11-24T10:22:42.547262433Z	stdout	[2022-11-24 10:22:42.546][lettre::transport::smtp::client::async_connection][DEBUG] << 220 2.0.0 SMTP server ready<CRLF>
2022-11-24T10:22:42.547189127Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] Wrote: STARTTLS<CRLF>
2022-11-24T10:22:42.547114338Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] server EXCHANGE2013.mycompany.local with {StartTls, EightBitMime}
2022-11-24T10:22:42.547010596Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>250-ENHANCEDSTATUSCODES<CRLF>250-STARTTLS<CRLF>250-X-ANONYMOUSTLS<CRLF>250-AUTH NTLM<CRLF>250-X-EXPS GSSAPI NTLM<CRLF>250-8BITMIME<CRLF>250-BINARYMIME<CRLF>250-CHUNKING<CRLF>250 XRDST<CRLF>
2022-11-24T10:22:42.546898453Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>250-ENHANCEDSTATUSCODES<CRLF>250-STARTTLS<CRLF>250-X-ANONYMOUSTLS<CRLF>250-AUTH NTLM<CRLF>250-X-EXPS GSSAPI NTLM<CRLF>250-8BITMIME<CRLF>250-BINARYMIME<CRLF>250-CHUNKING<CRLF>
2022-11-24T10:22:42.546765256Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>250-ENHANCEDSTATUSCODES<CRLF>250-STARTTLS<CRLF>250-X-ANONYMOUSTLS<CRLF>250-AUTH NTLM<CRLF>250-X-EXPS GSSAPI NTLM<CRLF>250-8BITMIME<CRLF>250-BINARYMIME<CRLF>
2022-11-24T10:22:42.546530101Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>250-ENHANCEDSTATUSCODES<CRLF>250-STARTTLS<CRLF>250-X-ANONYMOUSTLS<CRLF>250-AUTH NTLM<CRLF>250-X-EXPS GSSAPI NTLM<CRLF>250-8BITMIME<CRLF>
2022-11-24T10:22:42.546425637Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>250-ENHANCEDSTATUSCODES<CRLF>250-STARTTLS<CRLF>250-X-ANONYMOUSTLS<CRLF>250-AUTH NTLM<CRLF>250-X-EXPS GSSAPI NTLM<CRLF>
2022-11-24T10:22:42.546329675Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>250-ENHANCEDSTATUSCODES<CRLF>250-STARTTLS<CRLF>250-X-ANONYMOUSTLS<CRLF>250-AUTH NTLM<CRLF>
2022-11-24T10:22:42.546235867Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>250-ENHANCEDSTATUSCODES<CRLF>250-STARTTLS<CRLF>250-X-ANONYMOUSTLS<CRLF>
2022-11-24T10:22:42.546138140Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>250-ENHANCEDSTATUSCODES<CRLF>250-STARTTLS<CRLF>
2022-11-24T10:22:42.546045627Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>250-ENHANCEDSTATUSCODES<CRLF>
2022-11-24T10:22:42.545911187Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>250-DSN<CRLF>
2022-11-24T10:22:42.545619579Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>250-PIPELINING<CRLF>
2022-11-24T10:22:42.545525201Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>250-SIZE 104857600<CRLF>
2022-11-24T10:22:42.545364214Z	stdout	[2022-11-24 10:22:42.545][lettre::transport::smtp::client::async_connection][DEBUG] << 250-EXCHANGE2013.mycompany.local Hello [192.168.1.1]<CRLF>
2022-11-24T10:22:42.536425825Z	stdout	[2022-11-24 10:22:42.535][lettre::transport::smtp::client::async_connection][DEBUG] Wrote: EHLO vaultwarden<CRLF>
2022-11-24T10:22:42.535939354Z	stdout	[2022-11-24 10:22:42.535][lettre::transport::smtp::client::async_connection][DEBUG] << 220 EXCHANGE2013.mycompany.local Microsoft ESMTP MAIL Service ready at Thu, 24 Nov 2022 11:22:41 +0100<CRLF>

and the support string

### Your environment (Generated via diagnostics page)
* Vaultwarden version: v1.26.0
* Web-vault version: v2022.10.0
* Running within Docker: true (Base: Debian)
* Environment settings overridden: true
* Uses a reverse proxy: true
* IP Header check: true (X-Real-IP)
* Internet access: true
* Internet access via a proxy: false
* DNS Check: true
* Time Check: true
* Domain Configuration Check: true
* HTTPS Check: true
* Database type: SQLite
* Database version: 3.35.4
* Clients used: 
* Reverse proxy and version: 
* Other relevant information: 

### Config (Generated via diagnostics page)
<details><summary>Show Running Config</summary>

**Environment settings which are overridden:** SIGNUPS_ALLOWED, ADMIN_TOKEN


```json
{
  "_duo_akey": null,
  "_enable_duo": false,
  "_enable_email_2fa": false,
  "_enable_smtp": true,
  "_enable_yubico": true,
  "_icon_service_csp": "",
  "_icon_service_url": "",
  "_ip_header_enabled": true,
  "admin_ratelimit_max_burst": 3,
  "admin_ratelimit_seconds": 300,
  "admin_token": "***",
  "allowed_iframe_ancestors": "",
  "attachments_folder": "data/attachments",
  "authenticator_disable_time_drift": false,
  "data_folder": "data",
  "database_conn_init": "",
  "database_max_conns": 10,
  "database_timeout": 30,
  "database_url": "****/**.*******",
  "db_connection_retries": 15,
  "disable_2fa_remember": false,
  "disable_admin_token": false,
  "disable_icon_download": false,
  "domain": "*****://***********.********.*****",
  "domain_origin": "*****://***********.********.*****",
  "domain_path": "",
  "domain_set": true,
  "duo_host": null,
  "duo_ikey": null,
  "duo_skey": null,
  "email_attempts_limit": 3,
  "email_expiration_time": 600,
  "email_token_size": 6,
  "emergency_access_allowed": true,
  "emergency_notification_reminder_schedule": "0 5 * * * *",
  "emergency_request_timeout_schedule": "0 5 * * * *",
  "enable_db_wal": true,
  "extended_logging": true,
  "helo_name": "***********",
  "hibp_api_key": null,
  "icon_blacklist_non_global_ips": true,
  "icon_blacklist_regex": null,
  "icon_cache_folder": "data/icon_cache",
  "icon_cache_negttl": 259200,
  "icon_cache_ttl": 2592000,
  "icon_download_timeout": 10,
  "icon_redirect_code": 302,
  "icon_service": "internal",
  "incomplete_2fa_schedule": "30 * * * * *",
  "incomplete_2fa_time_limit": 3,
  "invitation_expiration_hours": 120,
  "invitation_org_name": "Vaultwarden",
  "invitations_allowed": true,
  "ip_header": "X-Real-IP",
  "job_poll_interval_ms": 30000,
  "log_file": null,
  "log_level": "debug",
  "log_timestamp_format": "%Y-%m-%d %H:%M:%S.%3f",
  "login_ratelimit_max_burst": 10,
  "login_ratelimit_seconds": 60,
  "org_attachment_limit": null,
  "org_creation_users": "",
  "password_hints_allowed": true,
  "password_iterations": 100000,
  "reload_templates": false,
  "require_device_email": false,
  "rsa_key_filename": "data/rsa_key",
  "send_purge_schedule": "0 5 * * * *",
  "sends_allowed": true,
  "sends_folder": "data/sends",
  "show_password_hint": false,
  "signups_allowed": false,
  "signups_domains_whitelist": "",
  "signups_verify": false,
  "signups_verify_resend_limit": 6,
  "signups_verify_resend_time": 3600,
  "smtp_accept_invalid_certs": true,
  "smtp_accept_invalid_hostnames": true,
  "smtp_auth_mechanism": "login,plain",
  "smtp_debug": true,
  "smtp_explicit_tls": null,
  "smtp_from": "**********.*****@********.**",
  "smtp_from_name": "Vaultwarden",
  "smtp_host": "************.********.*****",
  "smtp_password": "***",
  "smtp_port": 25,
  "smtp_security": "starttls",
  "smtp_ssl": null,
  "smtp_timeout": 30,
  "smtp_username": "********\\******",
  "templates_folder": "data/templates",
  "tmp_folder": "data/tmp",
  "trash_auto_delete_days": null,
  "trash_purge_schedule": "0 5 0 * * *",
  "use_syslog": false,
  "user_attachment_limit": null,
  "web_vault_enabled": true,
  "web_vault_folder": "web-vault/",
  "websocket_address": "0.0.0.0",
  "websocket_enabled": false,
  "websocket_port": 3012,
  "yubico_client_id": null,
  "yubico_secret_key": null,
  "yubico_server": null
}