Email deliverability
Terms about whether mail reaches its recipients.
- Acceptance rate
The share of sent messages that the receiving mail server accepted rather than rejected.
- Backscatter
Bounce messages sent to an innocent address because spam used it as a forged sender.
- Blacklist
A list of IP addresses or domains that mail receivers use to reject or flag mail; now more often called a blocklist.
- Blacklisting
Being added to a blocklist, or the act of adding a sender to one.
- Blocklist
A list of senders, usually IP addresses or domains, that receivers refuse or treat with suspicion.
- Bounce
A message that could not be delivered and was returned to the sender with a reason.
- Bounce rate
The percentage of sent messages that bounced.
- Bulk email
The same message sent to a large number of recipients at once.
- Catch-all
A mail domain set up to accept messages for any address at that domain, whether or not a mailbox exists.
- Custom domain (sending)
Your own domain used for sending and for links and images in email, instead of the provider’s shared domain.
- Dedicated IP
A sending IP address used by only one sender.
- Deliverability
How reliably your email reaches recipients’ inboxes rather than bouncing or landing in spam.
- Domain reputation
How mailbox providers rate a sending domain, based on its history of complaints, bounces, spam traps and authentication.
- Email authentication
Records and signatures (SPF, DKIM, DMARC) that let receivers check a message really came from the domain it claims.
- Email bounce handling
The rules your system follows when a message bounces.
- Email engagement
How recipients respond to your messages: replying, clicking, opening and forwarding.
- Email filtering
How incoming mail is sorted into the inbox, spam or other folders.
- Email infrastructure
Everything that sends your mail: domains, sending IPs, mailboxes, DNS records and the platform.
- Email rate limiting
Limits on how many messages or requests are allowed in a period.
- Email reputation
The overall trust mailbox providers place in a sender, combining the reputation of its domain and its sending IPs.
- Email sender
The identity a message comes from: the From name, the From address and the envelope sender that receives bounces.
- Email warm-up
Gradually raising your sending volume from a new domain or IP so providers learn to trust it.
- Feedback loop (FBL)
A service where a mailbox provider sends you a report each time one of its users marks your message as spam.
- Hard bounce
A permanent delivery failure, such as an address that does not exist.
- Inbox
The folder where new messages arrive for a mailbox.
- Inbox placement rate
The share of your messages that land in the main inbox rather than spam or another folder.
- IP reputation
How receivers rate a sending IP address from its past mail.
- IP warm-up
Raising the volume sent from a new IP address in steps so receivers learn to trust it.
- MAILER-DAEMON
The automatic sender name on bounce messages that a mail server generates.
- No-reply address
A sender address such as noreply@ that is not meant to receive answers.
- Postmaster
The standard mailbox, postmaster@yourdomain, that a mail domain should keep for reporting delivery problems; also the name of providers’ sender dashboards.
- Primary tab
Gmail’s main inbox tab, as opposed to Promotions, Social and Updates.
- Shared IP
A sending IP address used by several senders, typical of email platforms.
- Soft bounce
A temporary delivery failure, such as a full mailbox or a busy server.
- Spam complaint
A recipient marking your message as spam; the provider may pass it back to you as a complaint.
- Spam trap
An address set up to catch senders who collect or keep addresses without care.
- Suppression list
A list of addresses you must never send to: unsubscribes, hard bounces and complaints.
- Whitelist
A list of senders a recipient or system has approved so their mail is not filtered; now often called an allowlist.