18
votes
Accepted
What's the difference between SMTP server and SMTP Relay?
Their functions are mainly the same, but the subtle differences are based on where they are located in the mailchain, hence they support sligtly different usages.
SMTP Server is somewhat generic and ...
- 6,098
13
votes
Accepted
Why do I get DONE after AUTH LOGIN command to SMTP Server?
I banged my head against this problem for several days before finding out that openssl s_client interprets a Q character at the start of the password as a "quit" command and closes the connection.
If ...
- 256
11
votes
Accepted
Is it possible to have an IMAP account but use a different SMTP server?
It's possible. The two protocols are completely unrelated. IMAP doesn't care how you send mail, and SMTP doesn't care how you receive mail. In Thunderbird, the SMTP server settings work the same and ...
- 454k
9
votes
Accepted
Don't deliver mail to certain addresses
To discard email for a user or domain, add an appropriate line to the "transport" table - typically by adding a line like below to /etc/postfix/transport:
[email protected] discard:
domain....
- 70.8k
8
votes
Special characters in ssmtp password
There are still a number of outstanding bugs dealing with special characters on the AuthPass line in the /etc/ssmtp/ssmtp.conf file:
https://bugs.debian.org/cgi-bin/pkgreport.cgi?repeatmerged=no&...
- 1,432
7
votes
Accepted
Configuring imap account without smtp in thunderbird
This is behavior of Thunderbird is arguably poorly implemented, but you can add any account with any settings without contacting a server to verify those settings.
TL;DR -- After initial account ...
- 17.3k
7
votes
Accepted
How to get e-mail delivered at specific time, to the second
You can't
Because of how email works, this is entirely impossible.
Your mail client will deliver the message to your server, which will then pass the message on to another server, etc... until ...
- 20k
7
votes
How to get the maximum attachment size of a mail server which perform ip connection whitelisting?
Odd... I checked the email address with DNS Stuff's Mail Service Test Center tool and it showed the server was valid and accepted connections on port 25. I had no issue using the telnet command in ...
- 6,528
6
votes
Accepted
Does email you send or reply to contain privacy information that spammers could use?
Your outbound emails won't contain much personal information, but there are some things to be aware of:
Replying confirms to a spammer that your address is active, so you'll get significantly more ...
- 7,756
5
votes
What is the difference between Gmail SMTP port 465 and 587 in Mutt?
Port 465 is for implicit TLS while port 587 is for STARTTLS.
The prefer approach is to use port 587. Use port 465 if port 587 fails.
Tl;dr Use port 587 if you can, 465 if you can’t, 25 if you must.
...
- 18.7k
4
votes
Postfix allows unauthenticated users to send emails
You can force users to authenticate before send e-mails, changing not on the main.conf but on master.conf, adding the check on submission, for example, and reject everything:
-o ...
- 209
4
votes
Sending email through telnet SMTP
I can only guess at the OP's reason, but as a sysadmin in a hosting company I use it all the time to debug mail problems. The procedure is simple and described many places, for example https://...
- 170
4
votes
Accepted
Windows 7 is blocking telnet 25
Is the server you are trying to connect to inside your network?
Since you mention port 25, my guess is that it isn't and you are trying to access some external mail server. Most ISPs these days ...
- 20k
4
votes
Accepted
After opening port with ufw, nmap output shows port as closed
In nmap, a closed port means that the port is reachable, but there is no application listening to the port. Try to run
nc -l 25
(as root of course) and redo the scan.
If the firewall would be ...
- 2,537
4
votes
Accepted
Sending an email from Python using local Python SMTP server
Disclaimer
I expect that at least some of the information below will be redundant for you. Please bear with me. =)
smtplib vs. smptd
Python comes with two modules for dealing with email — smtplib ...
- 17.3k
4
votes
Accepted
Resolve email delivery issue on "From and EnvelopeFrom 2nd level mail domains are different". Is this a hosting provider issue?
After considerable research, today I answer myself: YES, it IS a hosting provider issue. Here are the reasons:
Today, SPF alone is not enough anymore to validate a sender for any serious email ...
- 7,529
4
votes
Accepted
Selecting SMTP server
I have my email provider that provides SMTP server. My Internet provider also provides SMTP server. Which SMTP server is better to use in this situation?
These days – always the email provider's.
...
- 454k
4
votes
Accepted
cURL: How do I set the email subject when using -F (multipart / attachment)
Although the documentation mentions HTTP only, the -H / --header option works for SMTP also.
So the way to set the email subject is to add this option to the command line:
-H "Subject: The files you ...
3
votes
Accepted
Can you close the SMTP port and still send emails?
You do not need to have the SMTP port - thatis, TCP 25 - open for incoming requests on the machine (e.g. your laptop) from which you're sending mail via a mailclient.
The SMTP port must be open only ...
- 4,494
3
votes
Accepted
What diagnosis steps can I do if my emails send, but are not received, not even as spam?
Email troubleshooting can be divided into "sender" and "recipient" issues.
Since you are able to send to other people the Sending side is probably working fine. You need to investigate the Recipient ...
- 291
3
votes
SMTP: when sending a linux command, does it execute on the server side or client side?
Neither. SMTP is an email transfer protocol only, and does not support running arbitrary commands on either side. (You might be confusing it with SSH or UUCP?)
That said, in general, if you send a ...
- 454k
3
votes
telnet to smtp . 421 4.3.2 Service not available Connection closed by foreign host
A 421 error returned from a mail server means there is a problem with the mail server setup - this effectively says to the client "I have a problem and can't cope with email now, try again later" - ...
- 70.8k
3
votes
Why do I get DONE after AUTH LOGIN command to SMTP Server?
Another workaround is to put a single space char before the password.
In my case the Authentication get successfully.
- 31
3
votes
Accepted
Is SMTP simply a protocol or a specific MDA?
SMTP stands for Simple Mail Transfer Protocol. So yes, it's a protocol. I assume "SMTP MDA" means "Mail Delivery Agent using SMTP", because in ancient times when sendmail was written there were also ...
- 16.9k
3
votes
Accepted
SPF - that is just limiting what IPs are allowed to relay?
Wikipedia Sender Policy Framework :
Sender Policy Framework (SPF) is an email validation protocol designed to detect and block email spoofing by providing a mechanism to allow receiving mail ...
- 481k
3
votes
Accepted
SSMTP can't establish a startssl connection from a Raspberry Pi
ssmtp is unmaintained software and has known TLS-related problems. Debian completely removed ssmtp from repositories several months ago, Ubuntu will follow.
The only reason it works in Ubuntu/Debian ...
- 454k
3
votes
Can email server bcc another user to outgoing mail automatically
Yes, this is absolutely possible, doesn't change regardless of whether you're using a web-mail client or a conventional email client, and cannot be worked around at all.
Once the email is sent to the ...
- 9,468
3
votes
Accepted
Can I use the SMTP server of the hosting provider instead of the domain name provider?
Your inbound SMTP server is resolved using only DNS records within your domain, so you can use any SMTP provider exactly like you can use any web hosting provider.
(In general, domain sale, DNS ...
- 454k
3
votes
Accepted
What port does windows 10 Mail app use for smtp server by default?
It will try connections based upon these 3 ports, and the one that succeeds is then setup.
The default SMTP port is 25, so if no port is specified, 25 is used. If you require SSL, port 25 cannot be ...
- 61.5k
3
votes
Accepted
How is it that Email Marketing Platforms like mailchimp are able send emails from me without me giving them my email password?
Most of these services need you to authenticate your email domain.
The process includes updating DNS records to add information that allows their servers to send mail from your address without being ...
- 66
Only top scored, non community-wiki answers of a minimum length are eligible