Delivery problems are solved by working through checks in order, not by changing settings at random. First it has to be clear where the message is lost: on sending, in transit, or already at the recipient. The sequence below covers most cases.
Start with the headers of a test message
Send a message to a mailbox on a different provider and open the original - in most mail interfaces the option is called show original or message properties. The headers show the results of the SPF, DKIM and DMARC checks and the address of the server that actually sent the message.
That eliminates half the hypotheses immediately. If the checks fail, the problem is in the domain settings. If they pass and the message is still in spam, the issue is reputation or content.
What to check, in order
- Headers of a test message: SPF, DKIM and DMARC results and the sending server address
- The domain MX records: do they match the service you use
- SPF: are all sending services listed and is the DNS lookup limit respected
- DKIM: is signing enabled in every service that sends mail
- DMARC: is a strict policy in place before the setup is complete
- Whether the server address appears on blocklists
- Whether site mail goes through configured SMTP rather than straight from hosting
- Whether campaigns include an unsubscribe link and whether the message is overloaded with links
The most common cause with website mail
A contact form usually sends mail through hosting functions and puts the visitor address in the From field. To the receiving side that looks like a message from a foreign domain sent by an unrelated server, and such mail almost always lands in spam.
The correct setup: your domain address as the sender, the visitor address in reply-to, and sending through the SMTP of your mail service with an application password. The message then passes the checks and looks legitimate.
When checks pass but mail still goes to spam
Look at reputation and at content. Bulk campaigns sent from the shared IP of a cheap service suffer from other people complaints. A sudden jump in volume also reads as suspicious: a new domain should be warmed up gradually rather than sending a thousand messages on day one.
In the message itself, a clear subject without promises or capitals, the ratio of text to links, the absence of link shorteners and an unsubscribe link in campaigns all matter. Messages that recipients report quickly damage the reputation of the whole domain.
Frequently asked questions
Mail arrives at one provider and not at another. Why?
Providers use different filters and weigh reputation differently. One may accept mail without DKIM while another sends it to spam. That is normal and usually means the domain is configured partly: enough for some rules and not enough for others.
How can we check whether the domain is on a blocklist?
What needs checking is not the domain but the IP address of the sending server, visible in the message headers. Public blocklist lookup services exist for this. If the address belongs to shared hosting, you can do little about its reputation, and the answer is to move to a dedicated mail service.
Will changing the mail provider help?
It helps when the problem lies in the sending server reputation or in hosting limits. But if the domain is misconfigured, moving changes nothing: SPF, DKIM and DMARC will have to be set up again in the new place. So diagnosis comes first, the decision to move second.
Let us sort out mail delivery
Send the domain and describe where exactly the mail is not arriving. We will review the records and the headers of a test message.
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