Deliverability insights
Best-practice checks MailBlastr runs against a sent email, split into Attention items and Improvements, to help your mail reach the inbox.
When you open a sent email in the MailBlastr dashboard, the Insights tab runs a set of deliverability best-practice checks against that message and flags anything that could keep it out of the inbox. Each check either passes (a green check) or returns advice. Results are grouped into two categories: Attention and Improvements.
Attention
Concrete changes to the message that improve deliverability. These are worth acting on for most sends.
Link URLs match the sending domain
Links in the body should point back to the same domain you are sending from. Mismatched URLs are a classic spam signal — if you send from @widgets.com, links should resolve to https://widgets.com.
DMARC record is valid
DMARC is a TXT record that tells receivers how to handle mail that fails SPF or DKIM. A valid policy builds trust and, since 2024, is required by Gmail and Yahoo for bulk senders. See Implementing DMARC; MailBlastr suggests a starter record on the domain page if you are unsure what to publish.
Include a plain-text version
A plain-text alternative makes your message readable in clients that do not render HTML and is a positive deliverability signal. Pass it via the text parameter on POST /emails. If you send only html and omit text, MailBlastr auto-generates a plain-text alternative from your HTML — though supplying your own text gives you full control over how it reads.
Avoid "no-reply" senders
A no-reply@ from-address signals one-way communication and lowers trust. Some providers weigh replies when filtering, so a monitored, reply-able address both helps deliverability and lets recipients reach you.
Keep the body size small
Gmail clips messages larger than ~102 KB, hiding the rest behind a "view entire message" link (which also breaks open tracking). This check reports the current size of your email so you can trim it.
Use full YouTube URLs
Gmail’s filters flag shortened youtu.be links as possible phishing. Use the full form — https://www.youtube.com/watch?v=abc123 instead of https://youtu.be/abc123.
Improvements
Practice changes worth considering when you are actively diagnosing a deliverability problem.
Send from a subdomain
Sending from a subdomain (e.g. mail.yourdomain.com) rather than the root domain segments your traffic by purpose, so a problem with one stream of mail does not drag down the reputation of the others.
Disable click tracking
Click tracking rewrites your links, which can occasionally trip phishing heuristics. For sensitive transactional mail — login links, email verification — turning click tracking off on the sending domain can improve inbox placement.
Disable open tracking
Open tracking injects a pixel, which some filters treat as a spam signal. Disabling it on the domain can help sensitive transactional mail slip past those filters.