Mail sending troubleshooting

Had a problem sending mail, as well Thunderbird as Outlook would not send mail. Got an error message about a timeout. Looked into the Outgoing Mail settings and it would send mail via port 465. So I installed telnet for Windows and found that I could connect to port 993, but not 465. Switching off all firewalls did not help. The culprit was the Telekom WLAN router called speedport, once we enabled all secure ports there it worked.