Postmark looks way overpowered for what I need.

@wmlutz Ghost requires Mailgun anyway

One thing that's tripped me up in the past (especially after moving server): you need to whitelist your IP in Mailgun, see https://help.mailgun.com/hc/en-us/articles/360012244474-IP-Allowlist

Have you already done that? If not go here https://app.mailgun.com/settings/ip-access-management to add your server's IP.

Also be sure to update the Email address of your app here too to match your support@ address (I can't remember exactly why I needed to do this, but when I moved it from https://bridport.news to https://westdorset.news that was one of the things I ended up needing to do):

@jdaviescoates got it! It was the IP allowlist.

Glad to be of assistance

@wmlutz said in Outbound SMTP (Transactional Email) Stopped Working - Invalid login: 535 Authentication failed:

mailgun's transactional email cost which is cents/mo.

I don't think I've ever paid anything yet as I've not yet gone over the 1000 free messages a month or whatever it is...

Last week I noticed a cloudron error that said:

Server is running out of disk space 2:30 PM

One or more file systems are running out of space. Please increase the disk size at the earliest.

/dev/root is at 97% capacity.

So I attempted to make my EC2 instance bigger (didn't solve the space problem, but that's for another thread). It did however change my IP address. I added the new IP to Mailgun and swaks started working properly in a few minutes.

Side note: @crazybrad I think we're mixing up marketing/bulk and transactional. I use transactional for my ghostcms so I can keep things behind an auth wall, trying to keep kids safe. My parents/members use it rarely, it's not even worth $12/mo compared to mailgun's transactional email cost which is cents/mo.

Thanks to all for the help.

Postmark looks way overpowered for what I need.

@wmlutz Ghost requires Mailgun anyway

One thing that's tripped me up in the past (especially after moving server): you need to whitelist your IP in Mailgun, see https://help.mailgun.com/hc/en-us/articles/360012244474-IP-Allowlist

Have you already done that? If not go here https://app.mailgun.com/settings/ip-access-management to add your server's IP.

Also be sure to update the Email address of your app here too to match your support@ address (I can't remember exactly why I needed to do this, but when I moved it from https://bridport.news to https://westdorset.news that was one of the things I ended up needing to do):

<** 535 Authentication failed

root@17221886-0501-4fa4-8aeb-8a3025067e25:/# swaks --auth \
       --server smtp.mailgun.org:587 \
       --au postmaster@mail.tjspto.org \
       --ap PASSWORD \
       --to EMAIL \
       --h-Subject: "Hello" \
       --body 'Testing some Mailgun awesomness!'
=== Trying smtp.mailgun.org:587...
=== Connected to smtp.mailgun.org.
<-  220 Mailgun Influx ready
 -> EHLO 17221886-0501-4fa4-8aeb-8a3025067e25
<-  250-bc2e5756fbc9
<-  250-AUTH PLAIN LOGIN
<-  250-SIZE 52428800
<-  250-8BITMIME
<-  250-SMTPUTF8
<-  250-PIPELINING
<-  250 STARTTLS
 -> AUTH LOGIN
<-  334 VXNlcm5hbWU6
 -> cG9zdG1hc3RlckBtYWlsLnRqc3B0by5vcmc=
<-  334 UGFzc3dvcmQ6
 -> NjIxNWJhOGYyZTZmMDFkZGE0MjAyZTZhYTEyMjM5MjQtZjYyMDIzNzQtMzNjYjQzZWY=
<** 535 Authentication failed
 -> AUTH PLAIN AHBvc3RtYXN0ZXJAbWFpbC50anNwdG8ub3JnADYyMTViYThmMmU2ZjAxZGRhNDIwMmU2YWExMjIzOTI0LWY2MjAyMzc0LTMzY2I0M2Vm
*** Remote host closed connection unexpectedly.
root@17221886-0501-4fa4-8aeb-8a3025067e25:/# 

root@17221886-0501-4fa4-8aeb-8a3025067e25:/# swaks --auth \
       --server smtp.mailgun.org:465 \
       --au postmaster@mail.tjspto.org \
       --ap PASSWORD \
       --to my-personal-email@gmail.com \
       --h-Subject: "Hello" \
       --body 'Testing some Mailgun awesomness!'
=== Trying smtp.mailgun.org:465...
=== Connected to smtp.mailgun.org.
<** Timeout (30 secs) waiting for server response
 -> QUIT
<** HTTP/1.1 400 Bad Request
<** Content-Type: text/plain; charset=utf-8
<** Connection: close
<** 
*** Remote host closed connection unexpectedly.
root@17221886-0501-4fa4-8aeb-8a3025067e25:/# swaks --auth \
       --server smtp.mailgun.org:587 \
       --au postmaster@mail.tjspto.org \
       --ap PASSWORD \
       --to my-personal-email@gmail.com \
       --h-Subject: "Hello" \
       --body 'Testing some Mailgun awesomness!'
=== Trying smtp.mailgun.org:587...
=== Connected to smtp.mailgun.org.
<-  220 Mailgun Influx ready
 -> EHLO 17221886-0501-4fa4-8aeb-8a3025067e25
<-  250-dc25da1f3901
<-  250-AUTH PLAIN LOGIN
<-  250-SIZE 52428800
<-  250-8BITMIME
<-  250-SMTPUTF8
<-  250-PIPELINING
<-  250 STARTTLS
 -> AUTH LOGIN
<-  334 VXNlcm5hbWU6
 -> cG9zdG1hc3RlckBtYWlsLnRqc3B0by5vcmc=
<-  334 UGFzc3dvcmQ6
 -> NjIxNWJhOGYyZTZmMDFkZGE0MjAyZTZhYTEyMjM5MjQtZjYyMDIzNzQtMzNjYjQzZWY=
<** 535 Authentication failed
 -> AUTH PLAIN AHBvc3RtYXN0ZXJAbWFpbC50anNwdG8ub3JnADYyMTViYThmMmU2ZjAxZGRhNDIwMmU2YWExMjIzOTI0LWY2MjAyMzc0LTMzY2I0M2Vm
*** Remote host closed connection unexpectedly.

swaks --auth \
       --server smtp.mailgun.org \
       --au postmaster@mail.tjspto.org \
       --ap PASSWORD \
       --to my-personal-email@gmail.com \
       --h-Subject: "Hello" \
       --body 'Testing some Mailgun awesomness!'
=== Trying smtp.mailgun.org:25...
*** Error connecting to smtp.mailgun.org:25:
***     IO::Socket::INET: connect: timeout
root@17221886-0501-4fa4-8aeb-8a3025067e25:/# 

Does that help?