SMTP Submission

[kevindods]

Hi All,

We have a number of users who are using wifi hotspots etc to send emails from various devices and keep running into issues with many ISPs of port 25 blocking. I saw this:

SMTP Submission Port

Which is a little old though possibly valid but after the changes since those days I wondered if anyone has a better/more recent solution for this? I don't want to lose port 25 for submission for those that use it successfully but I wanted to offer an in-house solution for these mobile users.

Thanks.

Kevin

[Klug]

What about adding the private network used by the hotspots as authorized networks in postfix ?

[kevindods]

Thanks. Yep that would work for the known, but these users are all over the world so we can't predict which networks would be used at any one time. Also would prefer a single solution to meet the problem that would not open us up to possible abuse and the resultant hassle with the all the open relay spam BLs. Interesting thought process though, thanks!

Just thought with increasing mobile access some Zimbra solution would be useful. Is this something others have come up against? Or am I missing a trick?

[Klug]

Sorry, I misunderstood.
Thought you had hotspots "inhouse".

Your users won't be happy with the WebUI ?
You could also use VPNs.
Or go the "unclean" way (another SMTP server on another non-standard port).

[kevindods]

The web ui is a possible for some eg laptops but not smartphones/pdas etc and even the laptop users tend to want offline use too so have an IMAP client running in preference. Using SSL as an option on SMTP would be one way to avoid port 25 but its not currently supported. Other than that all I can think of is another box that can validate users off Zimbra LDAP with a non standard port like 587. Just feels like a heavyweight solution to a small problem ;-)

K

[kirme3]

edit /opt/zimbra/postfix/conf/master.cf and uncomment the following lines:

#submission inet n - n - - smtpd
# -o smtpd_etrn_restrictions=reject
# -o smtpd_client_restrictions=permit_sasl_authenticate d,reject

Then bounce postfix:
postfix stop
postfix start

This will open up smtp submission on port 587. I believe this will require the users to authenticate before sending mail too.

Not sure if it's a supported method either.

[kevindods]

Thanks kirme3, I'll have a closer look at that and see how it works and report back to the thread for completeness!

Cheers

Kevin

[kirme3]

Can anyone from Zimbra comment if this is a supported method too?

[kevindods]

Hi all,

Its a bank holiday in the UK so we use the time to do maintenance. So as promised a note just to confirm this works perfectly for me using Port 587 and TLS. Now to cap it all it seems that with 4.05 WM5 also gets the full HTML message body from current version.

Many thanks for everyones help over the lastyear.

Happy New Year!

Cheers

Kevin