About this video

Addresses in this video are examples. File verification needs a paid account. BillionVerify is not affiliated with or endorsed by Mimecast, Proofpoint, Barracuda or Sophos.

Video transcript

1. 00:00Spotting a gateway

   Mimecast, Proofpoint, Barracuda and Sophos can all sit in front of a company's mail. The result then depends on how that gateway behaves. Here are the four cases, and what to do with each. We spot a gateway from the domain's mail records. The MX host name shows who receives the mail. You can read the same thing in the API, in the field called mx_records. Then behavior decides. We look at how the gateway treats your address, and how it treats a random address that shouldn't exist. That gives four cases.

2. 00:34The four cases

   Case one. The gateway accepts your address and refuses the random one. It's telling addresses apart, so its yes means something. The result is valid, with the reason smtp_deliverable. Case two. It accepts both. The gateway is in accept-all mode, so that yes proves nothing about one mailbox. The status is catch-all, the reason is gateway_accept_all, and it uses one credit. Case three. It accepts your address, but temporarily limits the random one. This happens with Mimecast and similar gateways. We keep the yes, so it's valid. The score is lower, because nothing proved the domain isn't catch-all. Case four. The gateway blocks the check. A block tells you nothing about the mailbox, so the status is unknown, and the reason is smtp_blocked. There's no charge, and trying again usually won't help.

3. 01:22Temporary replies

   Gateways also send replies that only mean wait. Mimecast can greylist the check. Proofpoint can say a directory lookup is still running. Both return unknown, and both can be tried again. In a file job, you don't have to do anything. Greylisting is retried automatically, and you're charged once, only when a definite result arrives. Through the API, use force_refresh on rows where retryable is true. Sophos has one more case. Some of its replies give no conclusion about the recipient. Those return unknown, with the reason smtp_unverifiable, and they aren't retryable. One setting can hide all of this. check_smtp is on by default in the API. Set it to false and the SMTP layers are skipped, so most addresses come back unknown. The MCP tools default to false, so pass true there.

4. 02:13Read your results

   In a results file, ev_status gives you the group, and ev_reason tells you the case. gateway_accept_all and mimecast_greylist name the cause directly. The other codes are general, because they also appear on domains with no gateway.

5. 02:27What to do

   Valid goes in your main send. Catch-all follows the rule you already use: important mail usually goes, and cold outreach is your call. A retryable unknown gets another try. A blocked unknown doesn't, so hold it or send with care. A gateway has no fixed result. Its behavior on that domain decides, so read the reason before you choose what to send.

6. 02:48Get started free

   20 free credits every day you use your account, up to 600 a month. No credit card required. Start at billionverify.com.

Featured in this video

• Email gateway
• Email security