Context
You have set up a service on your Winheberg VPS that needs to send emails, website notifications, monitoring alerts or a contact form, but the mails do not go out? Before hunting for a bug in your Postfix or Sendmail, know that it is probably normal, all SMTP ports are blocked by default on Winheberg VPSes.
This guide explains why we block these ports, how to check that this is indeed the cause, and how to request them to be opened if you have a legitimate use.
Blocking outbound SMTP ports is common practice among many hosts and cloud providers worldwide. It is not an arbitrary limitation, it is a collective protection measure against mass spam and against the degradation of the host's IP range reputation.
Prerequisites
- A Linux VPS with Winheberg in service
- Root access over SSH to test outbound connections
- A Winheberg client account with truthful information and a valid email address
Which ports are blocked?
Winheberg blocks by default the standard ports used by the SMTP protocol to send emails.
| Port | Protocol | Use |
|---|---|---|
| 25 | SMTP | Relay between mail servers (server-to-server) |
| 465 | SMTPS | SMTP with implicit TLS encryption |
The block only concerns outbound connections from your VPS toward other servers. You can still receive emails normally if you host an inbound mail server.
Why does Winheberg block these ports by default?
The SMTP protocol has historically been the main vector of spam on the Internet. Any compromised server can send millions of emails in a few hours, which raises several problems.
- Spam protection, preventing a compromised VPS from being hijacked to send spam at scale
- Reputation preservation of Winheberg's IP ranges, because if our IPs were blacklisted by major mail providers like Gmail or Outlook, none of our clients could send emails
- Compliance with the modern hosting standards expected by network operators and anti-abuse services
So this block is in your interest as much as ours. If our IPs stay clean, your emails land in inboxes and not in spam folders.
How to check that this is really the cause?
Before requesting an opening, make sure the SMTP block is indeed the cause and not a problem in your mail configuration.
Connect to your VPS over SSH and test the connections toward an external SMTP server, here Gmail.
timeout 5 bash -c "</dev/tcp/smtp.gmail.com/25" && echo "Port 25 open" || echo "Port 25 blocked"
timeout 5 bash -c "</dev/tcp/smtp.gmail.com/465" && echo "Port 465 open" || echo "Port 465 blocked"
If the commands return blocked or hang for 5 seconds with no response, the SMTP ports are indeed blocked and that is the cause of your problem.
Requesting the SMTP ports to be opened
If you have a legitimate use that requires sending emails from your VPS, you can request it from our team through a ticket in your client area.
For a request to be reviewed, your Winheberg client account must hold truthful information and a valid email address, your sending domain must be established for some time, and the SPF and DMARC records must be valid on that domain. Our team then carries out anti-abuse checks before any opening.
Opening the SMTP ports is tied to a specific VPS, not to your overall client account. If you have several VPSes with Winheberg and want to send emails from several of them, you will need to open one ticket per VPS concerned. Each request is reviewed independently.
The unblock is not permanent. Once opened, you are responsible for keeping a clean usage of your VPS. In case of abuse, our team may re-enable the SMTP block to protect the reputation of our IP ranges and the ecosystem of our clients.
1. Access the billing client area
Log in to https://billing.winheberg.com with your Winheberg credentials, then in the top menu hover over Assistance and click Open a ticket, or use the blue Open a ticket button at the top right.
2. Choose the Technical department
On the Open a ticket page, you see 4 available departments, Sales, Technical, Billing and Other. For an SMTP opening request, click Open a ticket in the Technical section.
The Technical department is open 7 days a week, so your requests are handled quickly. Do not choose Billing or Sales for this kind of request, it may lengthen the delay.
3. Fill in the ticket form
Once in the form, make sure to select the VPS concerned in the Produit lié field, then give a clear subject and a detailed message.
Here is the information to fill in your ticket.
| Field | What to enter |
|---|---|
| Ticket Department | Technical |
| Produit lié | The exact VPS for which you request the opening |
| Priority | Medium, enough for this kind of request |
| Subject | SMTP ports opening request |
| Message | The details of your intended use, see below |
4. Detail your request in the message
In the Message field, provide the following so our team can process your request.
- Intended use, describe precisely why you need to send emails, application notifications, contact form or monitoring alerts
- Estimated volume, the number of emails per day or per month you plan to send
- Sending domain, the domain name the mails will be sent from
- SPF and DMARC confirmation, you must confirm that the SPF and DMARC records are correctly configured and valid on your domain before the request
You can check the validity of your SPF and DMARC records with online tools like MXToolbox or Mail-Tester before opening the ticket. A complete file from the start speeds up processing.
5. Review by our team
Our team will review your request to make sure it is a legitimate use. This check is usually quick, but can take from a few hours to a few days depending on the ticket volume.
The more detailed and professional your request, the more likely it is to be accepted quickly. A vague ticket like "please open SMTP" will require additional information and lengthen the delay.
Troubleshooting
❌ My ticket was refused, what should I do?
A request may be set aside if the use is not clear enough, if the sending domain is not correctly configured, or if the client account holds incomplete information. Start by updating your client profile in the billing area with current information, check your SPF and DMARC DNS configuration, then open a new ticket detailing the following points.
- The exact service you use, Postfix, Sendmail or a custom application
- The type of emails you send, transactional, notifications or newsletter
- The precise volume planned
- Your domain and confirmation that SPF and DMARC are valid
- The VPS concerned selected in Produit lié
❌ I want to send many emails per day, will it go through?
For large volumes, more than a few hundred emails per day, our team will review your request with particular attention. You will need to justify the use, specify the type of emails, transactional, marketing or notifications, and demonstrate that your mail infrastructure SPF, DKIM and DMARC is correctly configured.
❌ The ports are open but my mails end up in spam
Opening the ports is not enough for good deliverability. You also need to set up the following records.
- An SPF record on your domain
- A DKIM signature to authenticate your emails
- A DMARC policy to indicate how to handle unauthenticated mails
Without these records, Gmail and Outlook will treat your mails as suspicious and send them to spam or reject them.
❌ I unblocked SMTP on one VPS but not on my other VPS
This is normal. Opening the SMTP ports is tied to a specific VPS, not to your overall account. If you want to send emails from another VPS, you need to open a new ticket for that VPS by selecting the right Produit lié in the form. Each request is reviewed independently, but if you already had a legitimate unblock on a first VPS, the second is generally handled faster.
❌ SMTP was unblocked then re-blocked
If your emails were going out correctly and suddenly stop, the block was probably re-enabled on your VPS. The unblock is not permanent, it can be removed in case of observed abuse, in order to protect the reputation of our IP ranges and the ecosystem of our clients. If you believe the re-enabling is a mistake, open a new ticket detailing the situation, backed by your mail server logs and your recent configuration.
❌ How long to get a reply to my ticket?
Generally, our team handles SMTP opening requests within a few hours to 48 hours depending on the volume. The more complete your ticket from the start, the faster it is processed, with no back and forth to ask for details.
Best practices
- Configure SPF, DKIM and DMARC on your domain even before requesting the SMTP ports to be opened
- Monitor blacklists with a tool like MXToolbox to check that your IP is not listed
- Limit the sending volume to what you actually need
- Secure your applications, contact forms and sending scripts to prevent an attacker from using your server to spam
- Document your mail infrastructure so you can troubleshoot quickly if something goes wrong
Need help?
If you are unsure whether you need to open the SMTP ports, or about your mail server configuration, our team is available. Open a ticket in the Technical department from your client area, fill the Produit lié field with the VPS concerned, and we will point you to the solution best suited to your need.
Your VPS is now ready to send emails in the best conditions 📧
