Meta navigation

Unable to send emails

Unable to send emails

Error message when sending e-mails

Does an error message appear when you try to send e-mail? You may need to adjust the settings in your e-mail program (e.g. Outlook, Mac Mail or smartphone app).

Please check whether the following details match your problem:

  • An error message appears only when you try to send e-mail, not when you receive e-mail.
  • You are using an e-mail program (e.g. Outlook or an app), not Webmail (i.e. e-mail in your Internet browser).
  • You are using an account from another provider (Gmail, Hotmail, GMX etc.), not Swisscom or
  • You are using an Internet (e.g. inOne home) or mobile phone subscription (e.g. inOne mobile, NATEL┬« data, etc.) from Swisscom for Internet access.

If all the above match, please follow the instructions below.

If some of the points do not match, we can help you on this page: Repair e-mail account.

Adjusting the settings of your e-mail client

  1. Open the settings in your e-mail program.

  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. 

If you cannot find these settings, you can use the manual instructions, which guide you through the settings of your e-mail program step-by-step.

Background information

SMTP (Simple Mail Transfer Protocol) is used, among other, for the connection between the terminal device (computer, tablet, smartphone) and mail server and communication between mail servers. Port 25 used to be 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 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 has decided to join in the fight against spam and to filter outgoing e-mails to e-mail servers via port 25 and only allows them under specific circumstances in its network (broadband, mobile network).

Customer Center

Manage your personal data, subscriptions and bills on your own.


My Swisscom Assistant

The worry-free service for your computer


Mobile Set up

Set up MMS, e-mail, Internet, Swisscom TV air and WLAN on your mobile phone.


Quick Check

Check up on your own Swisscom services such as TV, Internet, telephone, and email!