fix: use SMTP_SSL without SMTP_TLS for port 465

For implicit SSL on port 465, we need SMTP_SSL: true and should
NOT set SMTP_TLS (which is for STARTTLS on port 587).
Added SMTP_NO_MX_LOOKUPS to skip MX record lookups.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

asciinema/compose.yaml

@@ -20,6 +20,7 @@ services:
       SMTP_PASSWORD: ${EMAIL_SMTP_PASSWORD}
       SMTP_SSL: true
       SMTP_RETRIES: 2
+      SMTP_NO_MX_LOOKUPS: true
       MAIL_FROM_ADDRESS: ${EMAIL_FROM}
       MAIL_REPLY_TO_ADDRESS: ${ASCIINEMA_MAIL_REPLY_TO}
       SIGN_UP_DISABLED: ${ASCIINEMA_SIGN_UP_DISABLED:-false}