Resolved Email with attachments appear bigger: Can't send because of size limit

[mhache]

Hi.
Used the search tool but can't find a solution or something similar.
If i attach for exemple a 2.9MB picture to an email using RoundCube, Horde or Outlook the mail server see the email size as 3.9MB. This inflated size is causing issue with the Maximum message size that i set to 10000KB/10MB. Do you have an idea what could cause this? During my tests i sent a empty email with only the attachment in it.

dovecot 2.2.27-ubuntu16.04.17031716
dovecot-pigeonhole 0.4.16-ubuntu16.04.17031519
postfix 3.1.0-3ubuntu0.3
psa-horde 5.2.13-ubuntu16.04.build1705170314.14
roundcube 1.2.7-ubuntu16.04.build1705171113.11
Plesk Version Plesk Onyx v17.5.3_build1705170317.16 os_Ubuntu 16.04

Thanks.

 

[mhache]

I found the reason why:
Postfix mail size issue
"MIME encoding adds a 33.33% overhead to an attachment (3 bytes turn into 4 bytes). With a message size limit of 25 MB, the max attachment size is around 18 MB."

Its the MIME encoding overhead.