We are managing a Zimbra mail server Community edition. Since the IP Address reputation of our ISP is a bit poor, select domains (mail servers) are either blocking our emails which is resulting in loss of communication or mails not reaching .

However same domains have no issues receiving mass emails which were sent through a software using Amazon SES API.

Now we would like to send mails to select domains using Amazon SES API as an SMTP mail relay. However as far as users are concerned they should continue using MS outlook with current local Zimbra server as their SMTP.

We had earlier tried using another SMTP relay to send emails successfully using the same setup, but we don't know how we can use Amazon SES as a relay for select domains.

Note we don't want to send all mails using Amazon SES, only mails send to select domains, may be around 30 odd.

Any advice will be helpful.


Quite a good one, it requires fiddling with zimbra and postfix and unfortunately requires some manual configuration. I suppose you can handle the amazon stuff for getting an account.

all commands are done on the cli as the zimbra user. So login with ssh and become zimbra user by

su - zimbra

create an file for authentication to amazon:

echo email-smtp.eu-west-1.amazonaws.com awsauthuser:awsauthpass > /opt/zimbra/conf/relay_password
postmap lmdb:/opt/zimbra/conf/relay_password

Configure zimbra to use this username and password:

zmprov mcf zimbraMtaSmtpSaslPasswordMaps lmdb:/opt/zimbra/conf/relay_password
zmprov mcf zimbraMtaSmtpSaslAuthEnable yes
zmprov mcf zimbraMtaSmtpCnameOverridesServername no
zmprov mcf zimbraMtaSmtpTlsSecurityLevel may
zmprov mcf zimbraMtaSmtpSaslSecurityOptions noanonymous

Create a lookup file where you put the domains you want to send via amazon:

echo outlook.com smtp:email-smtp.eu-west-1.amazonaws.com > /opt/zimbra/conf/relay_amazon
postmap lmdb:/opt/zimbra/conf/relay_amazon

Of Course, you can add extra domains to the list above in an editor of your liking. Remember to run the postmap command after every change.

Tell zimbra to use the above mapping:

zmprov mcf zimbraMtaTransportMaps lmdb:/opt/zimbra/conf/relay_amazon,proxy:ldap:/opt/zimbra/conf/ldap-transport.cf

Activate the configuration

zmmtactl reload

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