Questions tagged [smtp]
SMTP is the Simple Mail Transfer Protocol, the most recent standard of which is defined in RFC 5321. It's the Internet standard for sending and receiving email.
3,186
questions
0
votes
1
answer
195
views
Warning: you may need to increase the main.cf smtp_destination_concurrency_limit - but it is set?
We have a huge delivery of emails right now and emails are not delivered as fast as I think they would:
In the mail log (Postfix v3.4.13 ) I see the following message
Dec 8 14:34:28 s29 postfix/qmgr[...
- 198
0
votes
3
answers
307
views
Is opening SMTP port with default Sendmail config safe?
My self-hosted web app (Ubuntu VPS) needs the ability to send noreply@ notifications to users when something goes wrong. I don't really need the ability to receive emails but I would like to comply ...
0
votes
1
answer
340
views
Can I generate and log output alerts for SMTP traffic using Suricata 7.0.2?
I have Suricata 7.0.2 IDS installed on a Linux Ubuntu 20.04 virtual machine. In my virtual environment, I have two virtual networks. In the first network, I have a mail user agent (Attacker) that ...
0
votes
0
answers
174
views
PAM failing to authenticate all users from one domain in dovecot
I have installed a mail server using Dovecot + Postfix, and it always worked correctly.
Recently I installed a new domain example.com and a user [email protected] for that domain in the mailserver ...
0
votes
2
answers
779
views
mailpit / kubernetes: SMTP sendmail cannot connect - telnet works fine
kuberntes setup:
mailpit service + deployment
(ingress works, I can connect to the UI)
---
apiVersion: v1
kind: Service
metadata:
name: desideria-crm-mailpit
namespace: desideria-crm
labels:
...
- 101
0
votes
0
answers
323
views
Can not setup postfix/dovecot with email clients
Having problems with configure postfix/dovecot with email clients such as outlook and thunderbird.
Using telnet and openssl I have tested both smtp and imap through ports 587 and 993.
Sent mails are ...
0
votes
0
answers
170
views
Setting up Windows Server 2019 to allow sending mail in Classic ASP/PHP
I'm working on migrating over to a new server and I'm trying to setup the server to allow PHP/Classic ASP to send emails from forms etc..
I followed these instructions and used the IP 127.0.0.1 where ...
- 121
0
votes
2
answers
1k
views
Email rejected by SMTP server
I am sending automatic emails with a custom written software. The recipient is VERY interested in receiving these emails, since they actively requested then. However, they are complaining they are not ...
- 807
0
votes
1
answer
237
views
Rewriting message header To: field when sending email
I am configuring an SMTP server with Postfix (v3.7.3) for local (i.e. host only) mail sending on openSUSE 15.5 Leap.
What I would like is to send messages to local "users" (there is no real ...
- 1
0
votes
0
answers
269
views
stunnel smtp tls frontend server/proxy for remote backend postfix
I'm running stunnel in server mode and listening on port 587 and trying to connect to a remote postfix server running on port 25.
NB: the two servers are connected via zerortier, which may or may not ...
google-cloud-platform
0
votes
2
answers
533
views
Can I Force Implicit TLS Connection For Port 587 On Postfix?
I have read many articles saying port 587 by default is explicit TLS. This means it's STARTTLS. It asks the server on an unsecured connection if TLS is supported and if it is, it continues with an ...
1
vote
1
answer
267
views
Wrap plain text mail in html
we use Postfix as MTA to send our mails from our system. Unfortunately we have an old persistent system which we cannot change, which sends mails to our customers in plain text format. I would like to ...
- 15
1
vote
1
answer
156
views
Exchange Online ESMTP responds differently from different clients - Windows 10 vs Windows Server 2019
When I telnet to our Exchange Online's SMTP server address (****.mail.protection.outlook.com, port 25) I get two different responses or types of connect depending on what machine I'm using.
When I ...
- 11
0
votes
3
answers
151
views
Postfix: How can I handle incoming mail for a single address, not the entire domain?
I've gotten my employer to configure the company-wide Exchange server to forward [email protected] to [email protected], a host I control. So far, so good. My Postfix configuration ...
- 131
0
votes
2
answers
3k
views
Postfix relay to Office 365 - DNS configuration
To reduce the likeliness of email being flagged as SPAM, I believe these are the few things that should be done on email servers:
Hostname resolves to a valid IP e.g. mail.example.com to 1.1.1.1
...
- 359