Configuring sendmail to allow SMTP traffic from my IP, domain, or email address
 

The goal is pretty simple. The situation is probably pretty common. I have multiple email accounts configured in my email client. Each is configured to use the SMTP server for the corresponding domain. Depending on the location of me and my laptop, I can send through some SMTP servers and not others. At work, I can send through work SMTP, at home I can send through my ISP SMTP server, etc...

If I'm at a random public wifi access point, I generally can't use any of my SMTP servers.

Naturally, I'd like to send mail from any location without having to go through and change my SMTP servers each time I go somewhere new.

I set up a local mail server on my laptop, and it works fine. But about 20% of the time, my mail is rejected as many servers block incoming mail from large ISP IP blocks.

Does anyone know how to configure a sendmail server to allow relaying from a specific domain/ip address/email address?

I have my own dedicated server, and I've tried to configure sendmail to relay messages from my laptop. I've configured rules in /etc/mail/access like:

None of this works.

From all the docs that I've read, sendmail really only wants to deliver mail to domains hosted on the server itself. I appreciate this anti-spam approach, but I want to send mail!

I'm sure there's someone as ignorant about sendmail as I am who has solved this very same problem in a simple way.

On a side note, are there SMTP service providers for users like me that someone would whole-heartedly recommend? If I can't get sendmail to do what I want, I'd happily pay a modest fee for someone else to provide the functionality I'm looking for. But it would have to be a very reputable company as I know this type of service would be a natural haven for spammers.

Related thread:

Configuring sendmail for mail forwarding to server