Deliverability is whether your email actually reaches the inbox instead of the spam folder or a hard block. It's part technology and part behavior. CMass handles the technical side for you; this guide explains what it does and the habits that keep your sender reputation healthy.
You send from your own Gmail — that's a head start
CMass sends every email through your own connected Gmail account using Google's API. That matters: your messages come from your real address, signed with Google's own SPF and DKIM, from Google's trusted mail servers. Many bulk-email tools send from their own shared servers, which inherit whatever reputation thousands of other senders have built — good or bad. With CMass, your reputation is your own.
Respect Gmail's sending limits
Google caps how many emails an account can send per day. CMass knows these limits and paces sending to stay under them:
- ▸Regular Gmail (@gmail.com): about 500 emails per day
- ▸Google Workspace (your own domain): about 2,000 emails per day
If your list is larger than your daily limit, CMass throttles and spreads the send so you don't trip Google's abuse protections. You can also set your own slower pace in the Settings tab (emails per day, or a pause between each email) to look even more natural.
Warm up a new or quiet account
If your account hasn't sent much bulk email before, don't go from zero to 500 on day one. Ramp up over a couple of weeks — start with smaller batches to engaged contacts and increase gradually. Mailbox providers trust senders whose volume grows steadily, not ones that spike overnight.
Keep your list clean
The fastest way to wreck deliverability is emailing addresses that bounce or people who never opted in. CMass helps automatically:
- ▸Bounce suppression — when an address hard-bounces, CMass records it and skips it on every future campaign, so you never repeatedly hit a dead address.
- ▸Reply detection — when someone replies, CMass pauses their follow-ups automatically, so you don't keep nudging someone who already answered.
- ▸Unsubscribes — people who opt out are suppressed from future sends automatically.
On your side: only email people who have a reason to hear from you, and remove obviously invalid or ancient addresses before importing.
One-click unsubscribe is built in
Every CMass campaign includes a List-Unsubscribe header with one-click support (the standard Gmail and Apple Mail now require for bulk senders). You should also include a visible unsubscribe link in your body using the {unsubscribe_url} merge tag. Making it easy to leave actually protects you — people who can't find an unsubscribe link hit 'Report spam' instead, and spam complaints are the single most damaging signal to your reputation.
Write emails that don't look like spam
- ▸Personalize — use merge tags (and AI personalization) so each email is relevant, not a generic blast.
- ▸Keep it conversational — a short, plain email from a real person outperforms a heavy, image-only marketing template and is far less likely to be filtered.
- ▸Avoid spam-trigger habits — ALL CAPS subject lines, walls of exclamation marks, 'FREE!!!', misleading subjects, or a single giant image with no text.
- ▸Balance text and images — if images are blocked, your email should still make sense.
- ▸Don't attach large files or use link shorteners that are common in spam.
Watch your numbers
Your campaign stats are an early-warning system. A rising bounce rate or spam-complaint signal means slow down and clean your list. Keep bounces under ~2%. If replies and opens are healthy and bounces are low, you can gradually increase volume.