Mailjet accepted your mail, so why does it land in spam?

Mailjet is a French email platform that handles both transactional and marketing mail. When Mailjet accepts a message, it has passed Mailjet's own checks. But acceptance at the sender is not the same thing as delivery to the inbox. The receiving provider (Gmail, Outlook, Yahoo) makes the final call based on your domain's authentication, your sending reputation, and the content of the message.

Here are the five most common reasons Mailjet mail lands in spam, in order of how often they show up.

1Your SPF record is missing the Mailjet include

Mailjet sends from its own IP ranges, so your SPF record must authorize Mailjet. If your SPF record does not include Mailjet, receiving servers see your mail as coming from an unauthorized source and flag it.

The fix is to add the Mailjet include to your SPF record. For most accounts that is include:mailjet.online. If you send from a specific region, the Mailjet dashboard shows the exact include to add.

v=spf1 include:mailjet.online ~all

Open your DNS provider, find the SPF record for the domain you send from, and add the Mailjet include. If you already have an SPF record, add the include to the existing record rather than creating a second one. Only one SPF record is allowed per domain, and a second one causes a permerror that hurts deliverability.

2DKIM is not enabled, or the CNAME record is missing

DKIM proves to the receiver that the message was actually sent by your domain and not altered in transit. Mailjet signs your mail with DKIM, but only if you have published the DKIM record in your DNS.

Mailjet's DKIM setup uses a CNAME record. The Mailjet dashboard gives you the exact CNAME value to add. It looks something like a selector name pointing to a Mailjet CNAME host. Without that record, DKIM verification fails and the mail is treated as unauthenticated.

3You are sending from a domain that is not verified in Mailjet

Mailjet requires you to verify each sending domain before it will send mail from it. Verification means proving you control the domain by adding a TXT record to your DNS. If the domain is not verified, Mailjet will either refuse to send or send with degraded authentication, and receiving providers will notice.

The fix is to complete domain verification in the Mailjet dashboard. Mailjet gives you a TXT record to add to your DNS. Once that record is live, Mailjet marks the domain as verified and your mail carries proper authentication.

4Shared IP reputation and no warm-up

By default, Mailjet sends from shared IP addresses. That means your mail shares the same IP reputation as every other Mailjet customer. If another customer on the same IP has a high spam rate, your mail suffers too, even if your own sending is clean.

Two fixes help here. First, warm up your sending volume gradually. Start with a small number of recipients per day and increase over 2 to 4 weeks. Sudden spikes in volume trigger spam filters. Second, if you send at scale, consider a dedicated IP from Mailjet, which gives you a reputation that is yours alone.

5Bounce and complaint rates are too high

Receiving providers track how often your mail bounces (the recipient no longer exists) and how often recipients mark your mail as spam. If your bounce rate is above 2% or your complaint rate is above 0.1%, providers will start filtering your mail to spam or blocking it entirely.

The fix is to clean your list. Remove addresses that have not opened your mail in 6 months, and suppress addresses that have bounced or complained. Mailjet's dashboard shows your bounce and complaint rates. If they are high, clean the list before sending again.