Re: [LUG] Email and SSL

[Grant Phillips-Sewell <dcglug@xxxxxxxxxxxxxxxxxxxxx>]

On Fri, Oct 26, 2018, 13:02 Neil <barnaby@xxxxxxxxxxxx wrote:

I have just added a new email account for myself. (This is one way to
keep things separate instead of too many filters.) Anyway, when I had a
look at the manual settings I noticed that it was recommended to use the
secure settings. I use IMAP and the only difference I could see was the
port numbers for the incoming servers. On most of my email accounts I
have port 143 set up for incoming emails. Just one account uses port
993. I have never noticed this before.

Can anyone comment on this please? If is is better to use port 993
because it is more secure, and I change that setting, will it cause me
any problems? The outgoing server is set to port 587, whereas the
recommendation is to use 465. I am using the Thunderbird client and
there is only one outgoing server for all accounts. At least, if there
is a way to have different outgoing servers for each account I have not
found it.

Or should I just not mess with it?

Neil

The port numbers are sort of irrelevant, but also quite important.

What I mean by that is that the port number is essentially a way to identify which service on the server you want to connect with. If you have control over the server then you can set it up to listen on any port you like. As such, port numbers are kind of irrelevant.

However, port numbers for various services have become standardised. For instance, 25 is the standard port for non-encrypted SMTP, 110 for non-encrypted POP3, 143 for non-encrypted IMAP4, 465 for encrypted SMTP, 587 is frequently also used for this, 995 for encrypted POP3, and 993 for encrypted IMAP4.

Often, but not always, using the wrong port number (say 143 when you still ticked the "use SSL" box) will result in the server rejecting the connection.

Grant.

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