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WelcoYour alerts, by text.

Secure email to SMS where only approved senders can text

Secure email to SMS means only approved senders can turn email into texts, so your on-call phone only buzzes for your own alarm systems. Your Welco address bounces mail from anyone else. A stranger, a spammer or the office copier can't reach your team. You approve each system's From address once.

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  • Approve each system once
  • Unknown mail is bounced
  • Refused mail uses no credits

Works by email with

  • Nagios
  • Microsoft 365 / Outlook
  • Google Workspace Groups
  • Data loggers

Approved senders only

Try it: turn it off and on.

3

An open address: any mail that reaches it turns into a text

1

Approved senders only: your alarm systems and nothing else

On. The phone gets 1 text.

With Approved senders only off, the phone gets 3 texts: Welco: [Plant 2] Compressor 4 high discharge pressure at 1:40 AM. Reply STOP to opt out. Welco: Copier-3F scan complete, 4 pages. Reply STOP to opt out. Welco: Your account statement is ready, click to view. Reply STOP to opt out. With it on, it gets 1: Welco: [Plant 2] Compressor 4 high discharge pressure at 1:40 AM. Reply STOP to opt out.
Animation: Approved senders only switched off and on. An open address: any mail that reaches it turns into a text. Approved senders only: your alarm systems and nothing else.

What approved senders change for the on-call phone

  • Strangers can't wake your team

    An alert address can leak or be guessed. Mail from anyone you haven't approved never becomes a text.

  • Office mail stays out

    Scan-to-email copiers, newsletters and spam are refused at the door, before any rule runs.

  • One faulty system can't drain the plan

    Set a daily or monthly limit per sender, so a looping server can't burn through your message credits.

  • Every refusal has a reason

    The feed names the sender and why it was turned away, such as Blocked: sender not in allowlist.

How Welco checks each alert email

The sender check runs first, before any other Welco feature acts on the email. Here is what happens to every message that reaches your address.

  • Approved or refused

    Each system sends from a From address, like scada@plant.example.com. Only approved addresses can become a text, and everything else bounces.

  • Sender checks recorded

    Welco records each email's SPF, DKIM and DMARC results. Those checks show whether a message really came from the domain it names.

  • Limits per sender

    A daily or monthly cap on one sender keeps a stuck alarm loop from spending a month of credits in one night.

  • One bill for every sender

    Approved senders are billed to the account owner's plan, however many systems you add.

How to approve a new sender in 3 steps

This takes a few minutes per system. Nothing changes on the system itself.

  1. Find the system's From address

    Open a recent alert email, or look in the system's mail settings. It's often something like alarms@, noreply@ or nagios@ at your own domain.

  2. Add it to your approved senders

    In Welco, add that address. When alerts arrive through a forwarding mailbox or a Google Group, approve the forwarding address, since that's the one Welco sees.

  3. Send a test alert

    Trigger a test from the system and look for it in the feed as accepted. Switch on test mode first if no real text should go out yet.

Lock your alert address to your own systems

Sign up, verify your business and approve the systems that may text your team.

7-day free trial, 15 message creditsCard required for verificationNo charge for 7 daysEmail reminder before billing

Approve my alarm systemsBook a demo

A real example: one alarm in, two strangers out

A plant's PLC gateway emails a compressor alarm. Its address is approved, so the alarm becomes a text for the on-call mechanic.

Alert email from plc-gateway@plant2.example.com, subject “ALARM Compressor 4”. Welco trims it to one text of 90 characters: “Welco: [Plant 2] Compressor 4 high discharge pressure at 1:40 AM. Reply STOP to opt out.”

Text received: Welco: [Plant 2] Compressor 4 high discharge pressure at 1:40 AM. Reply STOP to opt out.

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Animation: the alert email "ALARM Compressor 4" is trimmed into one text: "Welco: [Plant 2] Compressor 4 high discharge pressure at 1:40 AM. Reply STOP to opt out."

If a scan-to-email copier or a spam email hits the same Welco address, both are refused. Neither one reaches a phone or uses a message credit. On the phone side, a number only your alerts use makes real alarms easy to spot.

Setups where the approved address needs a second look

Most systems send from one fixed address. These four common setups need a little care.

Frequently asked questions

What does a refused sender see?

The sending mail server gets a bounce saying the message wasn't accepted. No text is sent and no credit is used. The Welco feed records the email and the reason, so you can approve the sender if it turns out to be one of yours.

Can someone fake an approved sender's address?

Faking a From address is possible with any email. Welco records SPF, DKIM and DMARC results for each email, which show whether it really came from that domain. Keep your Welco address private, the way you would a phone number.

Does Welco need a connection into our network or mail server?

No. Your system sends its alert email out, the same way it mails anyone else, and Welco only receives it. There is no agent to install, no inbound port to open and no login to your mail server. Approving the sender happens inside Welco.

Do I approve each monitoring server separately?

You approve each sending address, not each server. If ten servers send through one alerts mailbox, approve that one address. If each server sends from its own address, approve each one.

My alerts are forwarded through Outlook or a Google Group. Which address do I approve?

Approve the address the forwarded mail comes from, since that's what Welco sees. Our guides to Microsoft 365 forwarding and Google Groups alerts show where to find it.

Our logger vendor sends alerts for many companies from one address. Can other customers text us?

No. Welco tells accounts apart by the Welco address each email was sent to. A refused attempt gets a neutral bounce that doesn't reveal whether an account exists. The account owner is told about it separately.

Only your systems should text your team

Approve your alarm senders once and everything else is turned away.

Approve my alarm systemsBook a demo

7-day free trial, 15 message creditsCard required for verificationNo charge for 7 daysEmail reminder before billing