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the Forwarder have an attachment size limit ?

Comments

17 comments

  • mtindor

    I believe Gmail has a 25 MB max for incoming mails.   And you have to take into account mime-encoding (increasing the message size of messages with attachments by up to 33%).

    If you want to be forwarding emails off to Gmail, when they are originally sent by the sender the likely need to be 18 MB in size or less to make it through to Gmail.

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  • xqm2023

    From Gmail's side, I can successfully send a 24M size mail to my CPANEL email server. The mail received by the tank here is about 32M size. Then automatically transfer to the Zendesk mail server and Outlook through the setup. They are prompting that the attachment is too large, but I can directly send the mail to Zendesk or Outlook via Gmail mailbox.

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  • xqm2023

    Therefore, it can be determined that the forwarder has limited email size

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  • mtindor

    That's not how I see it.   Gmail indicates right in their docs that they allow no more than 25 MB

    From Gmail's site:

    You can send up to 25 MB in attachments. If you have more than one attachment, they can't add up to more than 25 MB.

    If your file is greater than 25 MB, Gmail automatically adds a Google Drive link in the email instead of including it as an attachment. Learn more about Google Drive attachment sharing settings.

    That is for sending.   On the receiving end (either direct or via a forward), they will only allow a message of 25 MB or less.

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  • cPRex Jurassic Moderator

    Sending out from Gmail isn't the same as receiving, so I'm not sure that proves anything.

    By default on the cPanel side we have this set to 50M:

    https://support.cpanel.net/hc/en-us/articles/360049860854-How-to-increase-the-maximum-allowed-attachment-size-in-Webmail

    but you can use the details there to adjust things.  However, if you get the error shown in the first post, the issue isn't on the cPanel side as it says Gmail is the one blocking the message.

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  • xqm2023

    1. I have already set the attachment size for EXIM and PHP to 50M or above.
    2. We were able to successfully send an email with an attachment size of 24M from Gmail to the CPANEL email server, but when viewed in the CPANEL inbox, the email size has increased to 32M. When viewed in the Gmail mailbox where it has already been sent, the email size has also increased from 24M to 32M. Gmail limits the size of attachments to 25M, which is correct.
    3. So what I want to confirm is whether the 32M emails received on the cpanel email server are forwarded by the sender's Gmail mailbox or by the cpanel setting the forwarding recipient's address for forwarding?
    Because there is a CPanel forwarder set up, my understanding is that the recipient's email address should be used to forward emails, rather than the sender's Gmail to achieve forwarding.

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  • cPRex Jurassic Moderator

    1 - Great!
    2 - It's normal for a forwarded message to increase in size as it would include all the headers of the previous forwarder.  6M seems like a lot, but I suppose it's possible.
    3 - It would be from Gmail - you could confirm this by checking the mail log in /var/log/exim_mainlog for that message.

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  • xqm2023

    2024-03-30 05:02:13 1rqJMZ-0009Gy-1F <= ****@gmail.com H=mail-pg1-f171.google.com [209.85.215.171]:52579 P=esmtps X=TLS1.3:TLS_AES_128_GCM_SHA256:128 CV=no S=33702328 id=CALOoUhtrywtZUqFvWUHey8YY6gjxE-LJK4OidVtB7NfEBWR2FQ@mail.gmail.com T="Parts issue" for ****@akasotech.com
    2024-03-30 05:02:13 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1rqJMZ-0009Gy-1F
    2024-03-30 05:02:13 SMTP connection from mail-pg1-f171.google.com [209.85.215.171]:52579 closed by QUIT
    2024-03-30 05:02:13 1rqJMZ-0009Gy-1F SMTP connection identification D=akasotech.com O=****@akasotech.com E=*****@akasohelp.zendesk.com M=1rqJMZ-0009Gy-1F U=akasotech ID=1003 B=redirect_resolver
    2024-03-30 05:02:13 1rqJMZ-0009Gy-1F Sender identification U=akasotech D=akasotech.com S=****@akasotech.com
    2024-03-30 05:02:13 1rqJMZ-0009Gy-1F SMTP connection outbound 1711746133 1rqJMZ-0009Gy-1F akasotech.com ****@akasohelp.zendesk.com
    2024-03-30 05:02:15 1rqJMZ-0009Gy-1F => cs <****@akasotech.com> R=virtual_user T=dovecot_virtual_delivery C="250 2.0.0 <****@akasotech.com> OOXnLFUsB2ZwiwAAOtl5Ug Saved"
    2024-03-30 05:02:15 1rqJMZ-0009Gy-1F [3.114.56.177] SSL verify error: certificate name mismatch: DN="/C=US/ST=California/O=Proofpoint, Inc./CN=*.smtp.a.cloudfilter.net" H="mail-pod-25.int.zendesk.com"
    2024-03-30 05:02:15 1rqJMZ-0009Gy-1F ** ****@akasohelp.zendesk.com (****@akasotech.com) <****@akasotech.com> R=dkim_lookuphost T=dkim_remote_smtp H=mail-pod-25.int.zendesk.com [3.114.56.177] X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no: SMTP error from remote mail server after MAIL FROM:<****@gmail.com> SIZE=34141079: 552 message size exceeds fixed maximum message size
    2024-03-30 05:02:15 cwd=/var/spool/exim 7 args: /usr/sbin/exim -t -oem -oi -f <> -E1rqJMZ-0009Gy-1F
    2024-03-30 05:02:16 1rqJMd-0009Iu-3A <= <> R=1rqJMZ-0009Gy-1F U=mailnull P=local S=4369 T="Mail delivery failed: returning message to sender" for ****@gmail.com
    2024-03-30 05:02:16 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1rqJMd-0009Iu-3A
    2024-03-30 05:02:16 1rqJMZ-0009Gy-1F Completed
    2024-03-30 05:02:16 1rqJMd-0009Iu-3A Sender identification U=mailnull D=-system- S=mailnull
    2024-03-30 05:02:17 1rqJMd-0009Iu-3A [142.250.114.26] SSL verify error: certificate name mismatch: DN="/C=US/ST=California/O=Proofpoint, Inc./CN=*.smtp.a.cloudfilter.net" H="gmail-smtp-in.l.google.com"
    2024-03-30 05:02:17 1rqJMd-0009Iu-3A => ****@gmail.com R=dkim_lookuphost T=dkim_remote_smtp H=gmail-smtp-in.l.google.com [142.250.114.26] X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no C="250 qJMerWKddnNCOqJMfrvQp3 mail accepted for delivery"
    2024-03-30 05:02:17 1rqJMd-0009Iu-3A Completed

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  • cPRex Jurassic Moderator

    That log confirms you are breaking the limit on the Gmail side of things:

    2024-03-30 05:02:15 1rqJMZ-0009Gy-1F ** ****@akasohelp.zendesk.com (****@akasotech.com) <****@akasotech.com> R=dkim_lookuphost T=dkim_remote_smtp H=mail-pod-25.int.zendesk.com [3.114.56.177] X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no: SMTP error from remote mail server after MAIL FROM:<****@gmail.com> SIZE=34141079: 552 message size exceeds fixed maximum message size

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  • mtindor

    Actually it looks like the email originally came in FROM Gmail, to an akasotech.com account, and then was forwarded out to Zendesk -- which blocked it for being too large of a message and then bounced it back to the Gmail address.

    So in this case I think Zendesk doesn't like the message size.

    Probably should turn on SRS (sender rewriting scheme) though.   That won't fix the problem with the message size.   But emails coming in from Gmail to akasotech.com and then being forwarded back out to some other mail service might eventually be blocked for DMARC.

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  • xqm2023

    1. Sending a 24MB attachment directly from Gmail to the Zendesk ticketing system works fine. Zendesk is able to receive attachments sent from Gmail.
    2. Sending a 24MB attachment from Gmail to the Akaso email and then forwarding it to the Zendesk ticketing system also works; Akaso email can successfully receive the attachment from Gmail. At this point, the received attachment size increases to 32MB. However, when forwarding it to Zendesk, there is an error message indicating that the attachment is too large. Zendesk limits attachments to a maximum of 50MB. This can be understood as Gmail restricting the size of outgoing attachments.
    3. There is a question regarding the forwarding mechanism: Is it possible to set up forwarding based on the recipient to achieve sending? Instead of the original sender sending the email because Gmail has a 25MB attachment limit. I have enabled SRS, but the original sender from Gmail still sends the email, and forwarding is unsuccessful due to the attachment being too large.

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  • cPRex Jurassic Moderator

    I guess I don't understand - aren't all forwarders based on the recipient? 

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  • xqm2023

    Since all forwards are based on recipients to forward emails.
    As the original sender, Gmail sends a 24MB attachment to the AKASOTECH mailbox, which is then forwarded to Zendesk by the recipient through a forwarder. Because the Akasotech email was able to successfully receive the 24MB attachment sent by Gmail, which increased to 32MB.
    So my understanding is that there will be no 32MB attachment size limit for forwarding to Zendesk via Akasotech email. I have already set it to 50MB, and zendesk also has a 50MB attachment size limit.
    That's not Gmail implementing forwarding, it's not about Gmail limiting 25MB attachments.

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  • cPRex Jurassic Moderator

    I'm not sure that helped my understanding at all :D

    So you want to change where the email gets forwarded to based on the sender?

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  • mtindor

    No matter what Zendesk says, it is Zendesk refusing to accept the mail.

     

    2024-03-30 05:02:15 1rqJMZ-0009Gy-1F ** ****@akasohelp.zendesk.com (****@akasotech.com) <****@akasotech.com> R=dkim_lookuphost T=dkim_remote_smtp H=mail-pod-25.int.zendesk.com [3.114.56.177] X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no: SMTP error from remote mail server after MAIL FROM:<****@gmail.com> SIZE=34141079: 552 message size exceeds fixed maximum message size
    2024-03-30 05:02:15 cwd=/var/spool/exim 7 args: /usr/sbin/exim -t -oem -oi -f <> -E1rqJMZ-0009Gy-1F

    That is the log entry showing the email being forwarded to Zendesk and the Zendesk mail system refusing to except it with "552 message size exceeds fixed maximum message size".

    This really has nothing to do with Gmail or cPanel.   In the end it's Zendesk not accepting it.

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  • xqm2023

    1. Send 24MB attachment directly from Gmail to ZENDESK ticket system. Zendesk can receive attachments sent from Gmail.
    2. Send 24MB attachments to CPANEL email from Gmail, and then forward it to the Zendesk ticket system; CPANEL email can successfully receive Gmail's accessories. At this time, the receiving attachment size increased to 32MB. However, when forwarding it to Zendesk, there will be an error message indicating that the attachment is too large. ZENDESK technology description Mail receiving attachment is limited to up to 50MB.

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  • cPRex Jurassic Moderator

    Correct, that still indicates an issue with Zendesk.

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