I'm working with a client who is currently travelling in Germany. He's able to receive mail on his POP Telus mail account, however he is unable to SEND messages. Running Windows 10 Pro, Outlook 2013. This isn't the first time I've run in to this; another client had the same issue in Amsterdam. Any ideas why this would be?
First off, Telus' webmail is always a backup if all else fails.
I had problems when trying to connect to Telus' SMTP server when not on a Telus network, until I went into settings and made sure the SMTP port was 1025, 587 or 465. Depending on the port, SSL may need to be on or off. If I recall 1025 is SSL off and 587 is SSL on. I'm not sure about port 465.
See these support documents for examples.
Depends on how you were accessing your email.
Using webmail always seems safe--log on to webmail.telus.net, see and send messages.
Using a mail client (Outlook, Outlook Express, Thunderbird, MS Mail, etc.) is a bit more problematic, and what you experienced in Mexico is a common problem in these cases.. Because a lot of spammers try to send messages from one server by going through another, many ISPs require any SMTP access (those are your outgoing messages) be through them, not through a "foreign" server, like Telus.
In some cases, it's sufficient to change your client's SMTP server from smtp.telus.net to whatever the ISP's SMTP server is (you can usually get this by searching for that ISP and "smtp server"). I've often done this and often it works well. Some ultra-cautious ISPs restrict their SMTP access to emails from their own customers, and that's a bigger problem. There's some work-around that I used to know, using GMail's SMTP server, but unfortunately I've forgotten it. Webmail is usually much less trouble, especially if your away-from-Telus trip isn't too long.
Often, talking with Tech Support at the "away" ISP can be useful. They should be aware of the nature of the problem, and (less often, I'm afraid) may have a suggestion.
Switching to a mail service that is primarily web-based (Outlook.com, GMail.com, etc.) should always work, but they really aren't particularly superior to Telus's own webmail, webmail.telus.net .