SMTP relay host with multiple smtp hosts (each for one account)

491810

I just got an email from Ionos that starting 14 of January 2024 I won't be able to send emails using my smarthost. When I called the support they argued that this is due to a change at Google and Microsoft mail whom wonÄt accept emails where the original sender and the emailadress do not match (because sendas was used). Searching the web I found different reasons why Ionos suspend the smarthost option in SMTP.

https://www.borncity.com/blog/2023/12/01/ionos-schafft-smtp-relay-smarthost-zum-15-januar-2024-ab/

Therefore I have to setup one mail account for each mailbox - or to switch my domain provider. This means that I have to have a corresponding mailbox at Ionos for each Grommunio mailbox. First I thought Ionos is just making money (5 accounts for another 2,49€/month) but when I called the support they told me that Gmail and Microsoft won't accept emails send via the "sendas"-option starting this date. So my question is how do I setup a 1:1 instead of a n:1 smtp relay host? Currently I have the following Line in my sasl_passwd:

smtp.ionos.de:587 firstname1@mydomain.ltd:ownpassword1234

Does anyone kno whether it's possible to setup a smtp relay host for each grommunio mailbox i.e.

firstname1@mydomain.ltd smtp.ionos.de:587 firstname1@mydomain.ltd:ownpassword1234
firstname2@mydomain.ltd smtp.ionos.de:587 firstname2@mydomain.ltd:ownpassword1234
firstname3@mydomain.ltd smtp.ionos.de:587 firstname3@mydomain.ltd:ownpassword1234
firstname4@mydomain.ltd smtp.ionos.de:587 firstname4@mydomain.ltd:ownpassword1234

(I'm from Germany and also speak German - so feel free to reply in German if your're German too)

crpb

If you already have relayhost = [smtp.ionos.de]:submission or similiar you can put in the configuration in the file configured in postconf smtp_sasl_password_maps (/etc/postfix/sasl_passwd or similiar i guess)

firstname1@mydomain.ltd firstname1@mydomain.ltd:ownpassword1234
firstname2@mydomain.ltd firstname2@mydomain.ltd:ownpassword1234
firstname3@mydomain.ltd firstname3@mydomain.ltd:ownpassword1234
firstname4@mydomain.ltd firstname4@mydomain.ltd:ownpassword1234

if you have multiple domains you can set individual servernames for each domain with e.g. postconf sender_dependent_relayhost_maps = hash:/etc/postfix/sender_relay and put something like this in it

domain1.tld [smtp.ionos.de]:submission
domain2.tld [smtp.1und1.de]:submission

that way you can use the default relayhost and anything configured in the sender_dependent_relayhost_maps will be looked up and used accordingly.

I just looked that up on an old kopano host but i think that was all that has to be done in general.

WalterH

ionos: https://www.frankysweb.de/ionos-stellt-smarthost-funktion-zum-15-01-2024-ein/

491810

WalterH

I saw that posting. That's why I started this posting to figur out how to setup a 1:1 instead n:1 configuration uprading my Ionos domain to a mail5-plan (5 mailboxes) for approx. 2,49€/month to cover my five mailboxes.

Howeveer several postings say that some Ionos support employees replied differently - some said (as to me) that I need to switch settings from n:1 to 1:1 when sending. Others were told that just the domain need to be the same (which is my scenario). Would be happy to get a clear answer. Also found this article regarding the Ionos changes:

https://www.msxfaq.de/internet/ionos_als_smarthost.htm

Just googled a bit and found a 3000 mail/month free plan on this webpage. Would cover my needs. So I signed up:

https://app.mailersend.com/

crpb

If you already use fetchmail as i presume you could just parse the fetchmailrc and generate the fitting sasl_passwd as described above automatically. I would rather stick with IONOS if you are already paying. That URL you posted doesn't even have an "Impress[um]". Maybe fine for personal use but i wouldn't dare to do that.

weini

not to forget
smtp_sender_dependent_authentication = yes
IIRC, this is not the default.

And even it MS & Google would not introduce their blocking, the 1:n setup is very desirable already today, as with 1:1 your emails will end up in spam filters on the receipient side very likely, since the supplying relay host does not match the sender domain in the 1:1 mapping case.