Plus Addressing and Gmail Dots: Are They Duplicates?
[email protected], [email protected] and [email protected] can all reach one inbox. What that means for your list, your sign-up form and your reports.
Look through any large list and you will find addresses like [email protected] or [email protected] next to [email protected]. Are they three people or one? The answer depends on the provider, and getting it wrong either inflates your numbers or throws away real contacts.
What plus addressing is
Many providers let you add a tag after a plus sign in the local part. Mail sent to [email protected] is delivered to [email protected]. People use it to sort mail or to find out who sold their address. Gmail, Outlook.com and several others support it. Some company mail systems do too; others reject the plus sign or treat it as part of the name.
Gmail and the dots
Consumer Gmail goes one step further: dots in the part before the @ are ignored. [email protected], [email protected] and [email protected] reach the same mailbox, and googlemail.com is the same service under another name. Do not assume this for other providers or for business domains: elsewhere a dot is a normal character, and [email protected] and [email protected] may belong to two people.
Why this matters for your list
- Duplicates that are not exact matches. The same person can be on your list three times and receive three copies of every campaign.
- Inflated numbers. Subscriber counts and conversion rates look better or worse than they are.
- Abuse of free offers. Someone can claim a one-per-person discount again and again with name+1@, name+2@.
- Suppression gaps. If a person unsubscribes with one variant, a variant of the same mailbox stays on the list.
Should you block plus addresses?
Usually not. Plus addressing is a legitimate privacy habit, and people who use it tend to be careful, engaged users. Blocking them means turning away good sign-ups. Instead, decide what you need:
- For deliverability: accept them. Every variant is still a working mailbox.
- For one-per-person offers: normalise the address before you compare. Remove the
+tag, and for gmail.com or googlemail.com also remove the dots. Compare that normalised value, but keep the address the person typed for sending. - For reporting: count people by the normalised value, not the raw string.
A simple normalisation rule
- Lower-case the whole address and trim spaces.
- Split at the last
@. - In the local part, cut everything from the first
+onwards. - If the domain is
gmail.comorgooglemail.com, remove every dot in the local part and treat the two domains as one. - Leave other domains as they are apart from the plus tag.
Store this normalised key in its own column next to the original address. That is all a duplicate check needs.
What verification can and cannot tell you
A verifier checks whether a given address can receive mail. It does not decide whether two addresses belong to the same person; that is a rule for your own data. A plus address returns the result of the mailbox behind it, and when a provider accepts every tag without confirming it, the result may be accept-all or unknown. Our bulk verification counts an address that is repeated exactly as written only once; variants that differ by a tag or a dot are separate addresses until you normalise them, so do that step before you upload if you want to pay for each mailbox once.
If you only want to remove exact repeats, no preparation is needed. If you want one row per real mailbox, normalise first, then verify. See the credit packs if you are planning a large clean-up.
