Article ID: 122494, created on Jul 28, 2014, last review on Mar 31, 2016

  • Applies to:
  • Plesk Automation 11.5
  • Plesk 12.0 for Linux


We set up 'Maximum message size' for Postfix node to 10 MB, and trying to send an email with 9 MB attachment file, but it is not working, why?


This parameter manages the following parameter in Postfix configuration (in command above it is shown in bytes while in Control Panel it is shown in kilobytes):

# postconf | grep message_size_limit
message_size_limit = 10240000

According to official Postfix documentation this parameter defines the maximal size in bytes of a message, including envelope information:

Additionally, the e-mail is a text-only protocol therefore all binary part of message (e.g. attachment) is base64-encoded. Base64 is always encodes 3 original bytes into 4 base64-bytes, so the attachment size during e-mail transfer is increasing in 1,25 times.

So in case if it is needed to allow to send an email with 10 Mb attachemnts you should increase the 'Maximum message size' considering the explanations above

Search Words

Maximum message size

horde message size exceeded fixed limit

maksimum mail size error

33a70544d00d562bbc5b17762c4ed2b3 56797cefb1efc9130f7c48a7d1db0f0c e0aff7830fa22f92062ee4db78133079 a914db3fdc7a53ddcfd1b2db8f5a1b9c caea8340e2d186a540518d08602aa065 29d1e90fd304f01e6420fbe60f66f838 2a5151f57629129e26ff206d171fbb5f e335d9adf7edffca6a8af8039031a4c7

Email subscription for changes to this article
Save as PDF