Do your invoices, quotes and one-time passwords fail to reach their recipients? We find the cause in DNS, authentication and reputation and fix it in the application and on the server. On request we run the mail servers for the long term.
Often more than one system sends in your name. CRM, newsletter service, helpdesk and application use the same domain, and not all of them are signed properly. Then invoices and one-time passwords land in spam or bounce.
The large providers now enforce their rules. Since November 2025 Gmail has stepped up enforcement and rejects non-compliant mail temporarily or permanently. Yahoo has required the same basics since February 2024, along with unsubscribing within two days. For domains that send 5,000 or more messages to Outlook.com, Hotmail, Live.com or MSN, Microsoft requires SPF, DKIM and DMARC. Otherwise it rejects the mail with error 550 5.7.515 (As of 2026-10, Microsoft (opens in a new window)).
You receive written results with priorities, a plan for DMARC and a measurement before and after the changes.
We check SPF, DKIM, DMARC, PTR, TLS and List-Unsubscribe, test with mailboxes at the large providers and record the starting state.
We find all systems that send in your name, including ones the IT department does not know about.
We correct SPF and DKIM in the application and on the server, add reverse DNS and TLS and set up the handling of bounces.
We take DMARC from p=none through p=quarantine to p=reject, without blocking your own emails, and then measure again.
| Date | Event | Source |
|---|---|---|
| 2024-02-01 | Gmail requires all senders to use SPF or DKIM, a valid PTR record, TLS and a spam rate below 0.3%. From about 5,000 messages a day, SPF, DKIM and DMARC (at least p=none) with alignment are required. | support.google.com (opens in a new window) |
| 2024-06-01 | Gmail: bulk senders that already had an unsubscribe link must offer one-click unsubscribe in marketing messages. | support.google.com (opens in a new window) |
We run Postfix and Dovecot servers and systems for transactional mail for practically all of our clients. Sending from applications is part of this, whether from ColdFusion, Lucee or PHP. The goal is delivery that is technically correct, compliant with provider policies and monitored.
A mail server for four company domains signed nothing, published no DMARC policy and was rejected by Microsoft. Our engineers audited it, piloted the change on one domain and rolled it out in batches. The result: all three checks pass at Gmail, the Microsoft block was lifted, and the users noticed nothing.
Services up, configuration valid, no errors in the system status. Yet phishing landed in the inboxes while partners' newsletters went to spam. Our engineers measured which detection mechanisms actually fired, repaired the causes, and three months later found and fixed a regression that only showed up hour by hour.
A delivery guarantee is not technically possible, because the receiving server decides. We make sure delivery is technically correct, compliant with the mailbox providers' policies and monitored. SPF, DKIM and DMARC are set up correctly. The reputation of your senders is watched, and every system that sends on your behalf is on record. After that we measure the result.
Linux is our main platform: Debian and Ubuntu, web servers, database clusters and virtualisation with KVM and Proxmox. We have run Windows Server with IIS in production since 2015. We recommend moving to Linux unless you prefer to stay with Windows.
You will receive a first reply within one working day. When we begin work depends on our current workload and on the scope. We give you a binding answer in the intro call. If it is urgent, the 48-hour emergency assessment starts as soon as we have access to the system.
It depends on scope, engagement model and urgency. Describe your situation briefly and, after a conversation, we will send you an offer. You do not need a budget for that. We quote fixed prices for the entry products.
For companies whose invoices, quotes or one-time passwords land in spam or bounce back as undeliverable.
We agree the scope and price in the intro call and confirm them in writing before we start. The fixes themselves and the ongoing operation of mail servers are not included. If you wish, we agree both afterwards.
A written action list with the causes and the fixes in order of priority, plus a plan for DMARC. Both are yours.
You tell us the goal and the current state, and we say openly whether and how we can help. Reply within one working day, no obligation.
Reachable: Monday to Friday, 9:00 to 17:00 Central European Time; support and emergencies around the clock (24/7)