Anti-spam warning

On this page:
What you can do if you get an anti-spam warning when you send e-mails. 

Solve problem

Step 1: Run through checklist:

Is this anti-spam warning displayed when you try to send e-mail?

Please check if the following points match your case:

  • A warning is only displayed when you try to send e-mails, not when you receive them.
  • You are using an e-mail program (e.g. Outlook, Apple Mail or an app), not Webmail (i.e. e-mail in your Internet browser).
  • You are using an e-mail account from another provider (Gmail, Hotmail, GMX etc.), not Swisscom or
  • You are using a Swisscom Internet or mobile subscription (e.g. inOne mobile, inOne SME Mobile, NATEL infinity, Natel data etc.).

None or only some points match your case? How to repair your e-mail account

All points match your case: Continue to Step 2:

Step 2: Adjust your e-mail program settings

  1. Open the settings in your e-mail program (e.g. Outlook, Apple Mail etc.).
  2. Change the port value to 587 (instead of 25) at "Outgoing mail server" or consult the help pages of your e-mail provider for the correct settings. Thanks to their encryption these settings may enhance security.

Why am I warned?

For security reasons.

SMTP (Simple Mail Transfer Protocol) is used for terminal device (computer, tablet, smartphone) and mail server connection, and also for communication between mail servers. Port 25 was previously used for both communication types, i.e. to send outgoing e-mails from e-mail programs (Outlook, Windows Live Mail, Thunderbird, etc.) to mail servers and then send to them from this mail server to the recipients' mail servers.

However, in the past port 25 was frequently misused for spam mail. In 1998 this resulted in a new standard, which now runs terminal device communication to mail servers via port 587 instead of port 25.

Swisscom takes the battle against spam seriously. For security reasons, we have decided to filter outgoing e-mails to e-mail servers via port 25 in our network and only allow them under specific circumstances.



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