|
FastMail Forum All posts relating to FastMail.FM should go here: suggestions, comments, requests for help, complaints, technical issues etc. |
|
Thread Tools |
9 Dec 2022, 08:57 PM | #1 |
Senior Member
Join Date: Oct 2015
Posts: 160
|
Disable subdomain addressing for an alias
I seem to remember that there is an option somewhere to disable the receiving of email for a particular alias that is using subdomain addressing for that alias.
Problem is I cannot find any such option. I have looked in the obvious places and at Fastmail help but cannot find it. Is/was there such an option or am I imagining things ? |
9 Dec 2022, 10:16 PM | #2 |
Member
Join Date: Sep 2022
Posts: 67
|
For an existing alias, go to Settings/Users & Aliases.
Find the alias, then Edit/Show advanced preferences. Enable check/tick the 'Reject' option. |
10 Dec 2022, 03:08 AM | #3 |
Intergalactic Postmaster
Join Date: May 2004
Location: Irving, Texas
Posts: 8,926
|
That is indeed how you can disable a particular alias, including all associated subdomain aliases.
Code:
if header :contains ["to", "cc", "resent-to", "x-delivered-to"] [ “bad1@store.example.com",“bad2@store.example.com"] { reject "Mailbox does not exist"; stop; } |
10 Dec 2022, 03:51 AM | #4 |
Senior Member
Join Date: Oct 2015
Posts: 160
|
Thanks both for your replies and in particular Bill for your always excellent replies.
I will just create simple rules to delete the subdomain messages. It would have been better if there was just a global option to reject all subdomain addresses but there isn't so I will have to live with it. The spammers are using different subdomain addresses each time (different values for bad in your reply above) so a specific rule may be pointless because the address in that rule probably won't be used again. Last edited by evfrson : 10 Dec 2022 at 04:18 AM. |
10 Dec 2022, 11:06 AM | #5 | |
The "e" in e-mail
Join Date: May 2003
Location: mostly in Thailand
Posts: 3,090
|
Quote:
|
|
10 Dec 2022, 06:48 PM | #6 | |
Senior Member
Join Date: Oct 2015
Posts: 160
|
Quote:
|
|
11 Dec 2022, 10:30 PM | #7 |
The "e" in e-mail
Join Date: Oct 2002
Location: Holon, Israel.
Posts: 4,837
|
I think that if the alias is in a user's own domain, one can set a bogus MX record for all subdomains, or for particular subdomains (i.e., refer the sender to a server that will reject the incoming email, or that does not exist at all. This would reject an email and would create a failure message for legitimate senders that would tell them the delivery failed, but would not create back-scatter as a result from a Joe Job attack as the delivery failure message is created by the sender and not by the receiver.
In case of a particular alias under a user's own domain, one can also create an NS record for the particular subdomain, then import the subdomain as a domain into fastmail, and then create aliases under that subdomain that can be set to anything that an alias can do, including disabled status, which would then reject all mail to that alias. For example, a user that has the privete domain example.org and wants to reject all email to addresses bad1@store.example.org and bad2@store.example.org would create an NS record for store.example.org pointing to Fastmail's name servers. Then import the domain store.example.org to Fastmail. Then create the aliases bad1 and bad2 in this domain and disable them (so they rejsect all email sent to bad1@store.example.org and bad2@store.example.or, and also to all addresses in the subdomains bad1.store.example.org and bad2.store.example.or). One would also probably set a catchall alias for the domain store.example.org so all email sent to other email addresses in this domain and it's subdomains will be received. |
Thread Tools | |
|
|