Use text-only emails. Plain text (rather than heavy HTML) reduces spam signals and improves deliverability.

Limit images and links, especially in the first email. On SMTP mailboxes, our built-in Global Custom Domain Tracking automatically replaces links with safe alternatives, so you don't need a third-party tracking domain.

Keep signatures minimal. Avoid extra domains, links, phone numbers, and photos, which spam filters weigh against you.

Avoid spam words. Check your copy — including the signature and any unsubscribe text — for trigger words.

Include a clear unsubscribe option in the email body. Maildoso's sending relay strips List-Unsubscribe/List-Unsubscribe-Post headers on every plan, so a header-based unsubscribe won't work — always include a visible, functional unsubscribe link or opt-out instruction directly in the body text to comply with regulations and avoid spam filters. For the full reasoning (including why PTR and DKIM work the same way) see Does Maildoso support List-Unsubscribe (one-click unsubscribe) headers?

Warm up properly and ramp gradually. Sudden volume spikes from a new domain are the fastest way to hurt reputation. See What's the daily email limit per email account? and How warmup works and how to start it.

Email clean, valid lists. High bounce rates and spam complaints damage reputation quickly.

Rotate campaigns and use spintax. Regularly refresh your copy and use plenty of spintax for variability.

Watch your scores. Track each mailbox's Google Score and Microsoft Score in the dashboard as you go — see Understanding your mailbox reputation scores. Emailing Microsoft recipients has its own tips: Landing in the inbox with Outlook and Microsoft recipients.

Pause mailboxes with high spam placement. If a mailbox shows poor placement during warmup, exclude it from campaigns until scores recover.- Leverage the deliverability audit table. Use the deliverability audit table to monitor email performance, including metrics like Date, Warmup Sends, and Cold Sends, to better analyze and optimize your campaigns.- Understand dynamic IP pools. Maildoso uses dynamically rotating IP pools, meaning sending IPs are not fixed and may change frequently. Manual reassignment of domains to specific IP pools is not possible. If you encounter issues such as Spamhaus listings, focus on proper warmup processes to resolve them

Authenticate your domain. Ensure SPF, DKIM, and DMARC records are correctly configured — even with perfect authentication, warmup is still required, as a single cold email to a new Gmail inbox can still land in spam.

First email: plain text, no links. Links and booking/drive links are fine in follow-ups once the thread exists — link tracking goes through our custom tracking domain.

Never use open tracking. The tracking pixel is an invisible image, which is a strong spam signal; turn open tracking off for the whole sequence in your sequencer. Click tracking on plain links is a separate matter and is acceptable.

Keep links out of the signature; at volume they become a footprint that filters learn.

Unsubscribe line: an opt-out sentence in the body is what we recommend for compliance (List-Unsubscribe headers are stripped by our relay — see Does Maildoso support List-Unsubscribe headers?). If placement drops on a long-running campaign, test a variant of your copy — identical copy sent for weeks gets "footprinted" by filters, and small rewrites restore placement more often than infrastructure changes.

Don't send to personal Gmail/Outlook.com/Yahoo lists — Maildoso is built for B2B delivery.