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My mother is trying to reconfigure her email client (Outlook Express) to send and receive emails because it has stopped working. Her email is from an ISP (say ISP1) whose dial up service she no longer uses (she retains the account for email and web space only). She uses another ISP (ISP2) to connect to the internet. ISP1 are advising her on how to reconfigure Outlook Express and they say she needs to know the "outgoing server name" from ISP2. ISP2's technical support do not know what this term means :(.

This doesn't make much sense to me -- I thought you would just need to know the mail server addresses from ISP1.

Is there anything difficult about setting up email in this way where you are using a different ISP to connect to the internet from the one who runs the email service?


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up vote 3 down vote accepted

Outgoing mail requires a connection to a SMTP server on port 25, and some ISPs (notably DSL and cable providers) block port 25 to anywhere but their SMTP servers. This means that email must be sent out via ISP2 even if the account in the From header is hosted by ISP1.

I don't have much confidence in ISP2's support though, if they can't connect "outgoing" with "SMTP"...

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Some ISPs will offer secondary ports to connect to their SMTP servers on, such as 587, or any other trivial port, in case their customers have to connect from secondary locations such as hotspots where port 25 is blocked. – MaQleod Apr 2 '11 at 12:17
To add to @MaQleod 's comment, 587 has in fact become the standard port for submitting mail as per RFC 4409. (It is required to use SMTP-AUTH to avoid the need to block it entirely.) Port 25 is now recommended to be only used for mail exchange between two servers. – grawity Apr 2 '11 at 16:53

ISPs jealously guard their outgoing email servers and only ever allow outgoing email to be sent from their own customers. This is to help to reduce the amount of spam on the internet and is to be applauded.

As a result your mother will not be able to send email out through ISP1 but will have to use ISP2 to send email.

Incoming email is another matter, however, and you can use either ISP1 or ISP2 for incoming email (ISP1 for her 'old' email address, and ISP2 for her 'new' one provided by ISP2).

The outgoing server for ISP2 will be named something like or where is the domain name that ISP2 use (,,, whatever).

The phrase to ask technical support at ISP2 is:

What is the address of your outgoing SMTP server for sending email?

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