problems sending mail outside of home network

Hi

I currently use mac mail to send and recieve mail from 2 yahoo accounts and 3 other personal and business accounts.

All works fine and smoothly at home on our home wireless network, but whenever I step outside of that network, for example now, when Im on another companies wireless network, everything else works, internet, messaging, receiving mail, but I just cannot send.

Im sure Ive never had this problem before..

Any ideas what it could be?

Cheers
Mark

For sending mail, you need a SMTP server. If you were using the Yahoo accounts from the web, you are using their SMTP server. If you bring in the Yahoo account into Mail, you are doing so either through POP or IMAP and Yahoo doesn't bring all their SMTP server as well.

In your home network, you are using your ISP's SMTP server (smtp.comcast.net for example) to send your emails.

When you go to any company, you will not have access to their SMTP/Mail server. Now you say you have some personal/business accounts. Depending on who you are hosting that with, they might have a SMTP server that you could access as long as you have Internet access.

For example, I run many websites and host my personal/business email accounts on (mt) Media Temple - Web Hosting Built to Scale. and they have a SMTP server that I could use if I wasn't on my home network..

Hope I explained it without rambling too much..

Regards

Hey, thanks for your reply.

that kind of makes sense, but I've previously not had a problem with this so am a little confused as to why its kicked in now, other than its this particular company network thats causing problems?

Im with media temple too and non of three addresses that I have with them will successfully send.

I can send from all 5 from my iphone with the same settings.
Is there any connection there?

If the issues are with one particular company's network, it's possible that they are controlling the outbound traffic on port 25 (SMTP) to ensure there's no spamming or they are monitoring all outgoing email traffic.

With the iPhone, are you also on the company's wireless network or 3G network? If the wireless, that's a little confusing indeed..

Regards

No, the iphone is on 3G

I've actually got all my outgoing mail routed via port 587.
Would that make a difference?

I'll have to check with the tech guys here, but I've a feeling you might be right with them blocking outgoing mail perhaps.