# "SMTP on Zerops"


## Keywords
smtp, email, mail, sendgrid, mailgun, ses, gmail, port 587, starttls, send email

## TL;DR
Only port **587** (STARTTLS) is allowed for outbound email — ports 25 and 465 are permanently blocked. Use an external email service.

## Port Configuration
| Port | Status | Protocol |
|------|--------|----------|
| 25 | **Blocked** | Traditional SMTP (spam risk) |
| 465 | **Blocked** | Legacy SMTPS (deprecated) |
| **587** | **Allowed** | SMTP submission with STARTTLS |

## Provider Configurations

| Provider | Host | Port | Username | Password |
|----------|------|------|----------|----------|
| Gmail | smtp.gmail.com | 587 | user@gmail.com | App password |
| Google Workspace | smtp-relay.gmail.com | 587 | user@domain.com | Regular/App pass |
| Office 365 | smtp.office365.com | 587 | user@domain.com | Account password |
| SendGrid | smtp.sendgrid.net | 587 | `apikey` | API key |
| Mailgun | smtp.mailgun.org | 587 | postmaster@domain | Password |
| Amazon SES | `email-smtp.{region}.amazonaws.com` | 587 | Access key | Secret key |

## Configuration Example
```yaml
envVariables:
  SMTP_HOST: smtp.sendgrid.net
  SMTP_PORT: "587"
  SMTP_USER: apikey
envSecrets:
  SMTP_PASSWORD: <sendgrid-api-key>
```

## Gotchas
1. **Port 25 is permanently blocked**: Cannot be unblocked — use 587 with STARTTLS
2. **Port 465 is also blocked**: Legacy SMTPS is deprecated — use 587
3. **Gmail needs App Password**: Regular Gmail passwords won't work — generate an App Password in Google Account settings

## See Also
- zerops://guides/firewall
- zerops://guides/environment-variables